New_bench-mark

Here are the list of circuits we can implement to reach [[Goal]] 

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Below is a list of circuits suitable for SPICE simulation, categorized by complexity levels based on the number of MOSFET transistors used. Each circuit includes a brief description focusing on how it's realized using NMOS, PMOS, or CMOS technology to aid in your understanding and implementation.

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### **Easy Level (<10 Transistors)**

1. **CMOS Inverter (NOT Gate)**
   - **Description:** Uses one NMOS and one PMOS transistor connected in series between Vdd and ground. Input is connected to both gates; output is taken from the connection between the transistors. When the input is high, NMOS conducts, pulling output low; when input is low, PMOS conducts, pulling output high.

2. **CMOS NAND Gate**
   - **Description:** Consists of two PMOS transistors in parallel (connected to Vdd) and two NMOS transistors in series (connected to ground). Output is low only when both inputs are high; otherwise, it's high.

3. **CMOS NOR Gate**
   - **Description:** Features two PMOS transistors in series (connected to Vdd) and two NMOS transistors in parallel (connected to ground). Output is high only when both inputs are low.

4. **Transmission Gate**
   - **Description:** Comprises one NMOS and one PMOS transistor in parallel, controlled by complementary gate voltages. Acts as a bidirectional switch with minimal resistance when enabled.

5. **SR Latch**
   - **Description:** Implemented using cross-coupled CMOS NOR or NAND gates. Stores a single bit of data, changing state based on set and reset inputs.

6. **CMOS Buffer**
   - **Description:** Two inverters connected in series (total of four transistors). Strengthens signal integrity by restoring voltage levels.

7. **CMOS XOR Gate**
   - **Description:** Realized using eight transistors. Combines PMOS and NMOS networks to output high when inputs are different.

8. **CMOS XNOR Gate**
   - **Description:** Similar to XOR gate but outputs high when inputs are the same. Uses eight transistors in CMOS logic.

9. **Current Mirror**
   - **Description:** Uses two matched NMOS or PMOS transistors. One transistor sets the reference current; the other copies it, providing consistent current in circuits.

10. **Differential Pair**
    - **Description:** Two NMOS transistors with common sources and differential inputs at the gates. Used in amplifier stages for comparing voltages.

11. **Level Shifter**
    - **Description:** Translates voltage levels between circuits using NMOS and PMOS transistors arranged to handle different voltage domains.

12. **Ring Oscillator (3-stage)**
    - **Description:** An odd number of inverters (three CMOS inverters) connected in a loop. Generates an oscillating output signal due to the inversion delay.

13. **Schmitt Trigger**
    - **Description:** A comparator circuit with hysteresis implemented using CMOS transistors. Provides noise immunity by introducing two different threshold voltages.

14. **Common Source Amplifier**
    - **Description:** A basic amplifier using a single NMOS transistor with the source connected to ground and a resistor load connected to the drain.

15. **Diode-Connected MOSFET**
    - **Description:** A MOSFET with gate connected to drain, acting as a diode. Used in current mirrors and voltage reference circuits.

16. **Pass Transistor Logic**
    - **Description:** Uses NMOS transistors to pass logic levels. Gate controls the conduction between drain and source, allowing signal flow when enabled.

17. **Voltage Divider using MOSFETs**
    - **Description:** MOSFETs operated in the linear region act as resistors to divide voltage levels.

18. **Half-Adder**
    - **Description:** Combines XOR and AND gates (implemented in CMOS) to perform single-bit addition, outputting sum and carry bits.

19. **Simple RC Oscillator with MOSFET Switch**
    - **Description:** Uses a resistor, capacitor, and a MOSFET acting as a switch to generate oscillations.

20. **Sample and Hold Circuit**
    - **Description:** Utilizes a MOSFET as a switch and a capacitor to sample an analog voltage and hold it for a period.

21. **Voltage-Controlled Resistor**
    - **Description:** A MOSFET operated in the linear region, where the resistance between drain and source is controlled by the gate voltage.

22. **Active Load**
    - **Description:** Uses a MOSFET configured to act as a dynamic resistor, providing better performance than passive resistors in amplifier circuits.

23. **Pull-Up/Pull-Down Network**
    - **Description:** Networks of PMOS (pull-up) or NMOS (pull-down) transistors used in CMOS logic to drive output nodes to Vdd or ground.

24. **Voltage-Controlled Current Source**
    - **Description:** A MOSFET provides a current proportional to the gate voltage, acting as a current source in circuits.

25. **Logic Level Converter**
    - **Description:** Converts logic levels between different voltage domains using NMOS and PMOS transistors arranged appropriately.

26. **Simple Voltage Reference**
    - **Description:** Uses diode-connected MOSFETs to generate a reference voltage less affected by supply variations.

27. **Switch Debouncer**
    - **Description:** Implements a circuit with MOSFETs to eliminate bounce in mechanical switch signals.

28. **Clamped MOSFET Switch**
    - **Description:** A MOSFET switch with additional transistors to protect against voltage spikes and ensure proper operation.

29. **Voltage Follower (Source Follower)**
    - **Description:** An NMOS transistor with gate as input and source as output, providing high input impedance and unity gain.

30. **Basic Charge Pump**
    - **Description:** Uses MOSFETs and capacitors to generate higher voltages from a lower supply voltage through charge transfer.

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### **Medium Level (10-25 Transistors)**

1. **Full Adder**
   - **Description:** Adds three one-bit numbers (A, B, Cin). Implemented using CMOS logic gates (XOR, AND, OR), typically requiring about 20 transistors.

2. **2-to-4 Decoder**
   - **Description:** Converts 2-bit binary input to four unique outputs. Realized using NMOS and PMOS transistors to create the necessary logic gates.

3. **D Flip-Flop**
   - **Description:** A memory element that captures the value of the D-input on a clock edge. Implemented with transmission gates and inverters in CMOS technology.

4. **Current Mirror with Cascode**
   - **Description:** Enhances a basic current mirror by adding cascode transistors for higher output resistance and better current matching.

5. **Differential Amplifier with Current Mirror Load**
   - **Description:** Combines a differential pair with a current mirror load to increase gain and improve balance in analog circuits.

6. **Ring Oscillator (5-stage)**
   - **Description:** Five CMOS inverters connected in a loop to generate a stable oscillation frequency.

7. **Operational Transconductance Amplifier (OTA)**
   - **Description:** Outputs a current proportional to the differential input voltage. Realized using differential pairs and current mirrors.

8. **Voltage-Controlled Oscillator (VCO)**
   - **Description:** An oscillator whose frequency is controlled by an input voltage, using MOSFETs in the timing circuit.

9. **CMOS Multiplexer (4:1)**
   - **Description:** Selects one of four inputs to pass to the output based on two select lines. Implemented using transmission gates and logic gates.

10. **Bandgap Reference**
    - **Description:** Provides a stable voltage reference over temperature variations. Uses multiple transistors to combine voltages with opposite temperature coefficients.

11. **Schmitt Trigger with Hysteresis Control**
    - **Description:** An improved Schmitt Trigger circuit with adjustable hysteresis achieved by modifying transistor ratios.

12. **Charge Pump with Multiple Stages**
    - **Description:** Generates higher voltages using several stages of capacitors and MOSFET switches controlled by clock signals.

13. **Low Dropout Regulator (LDO)**
    - **Description:** Provides a regulated output voltage using a PMOS pass transistor and error amplifier to control gate voltage.

14. **Gilbert Cell Mixer**
    - **Description:** An analog multiplier circuit used in RF applications, implemented using differential pairs and current sources.

15. **Phase Detector**
    - **Description:** Compares the phase of two input signals, outputting a voltage proportional to the phase difference. Uses mixers or logic gates in CMOS.

16. **Level Shifter with Cascode**
    - **Description:** Transfers signals between different voltage levels while protecting transistors from high voltages using cascode configurations.

17. **Sample and Hold Circuit with Buffered Output**
    - **Description:** Adds a buffer stage to the basic sample and hold circuit using an additional MOSFET source follower for better load driving capability.

18. **Voltage-Controlled Attenuator**
    - **Description:** Adjusts signal amplitude based on a control voltage using MOSFETs as variable resistors.

19. **Pulse Width Modulator (PWM)**
    - **Description:** Generates a pulse width proportional to an input voltage using comparators and a ramp generator implemented with MOSFETs.

20. **Flash Analog-to-Digital Converter (ADC)**
    - **Description:** Uses multiple comparators (built with differential pairs) to convert an analog input into a digital output in parallel form.

21. **CMOS Latch**
    - **Description:** Stores data using cross-coupled inverters and transmission gates, allowing data retention even when the input is removed.

22. **RC Oscillator with MOSFET-based Amplifier**
    - **Description:** Utilizes a resistor-capacitor network and a MOSFET amplifier to create a sinusoidal oscillator.

23. **Active Filter (e.g., Low-Pass Filter)**
    - **Description:** Uses MOSFETs in amplifier configurations to achieve desired frequency responses, allowing for signal filtering.

24. **Delay Line**
    - **Description:** A series of buffers or inverters (using CMOS logic) that delay the input signal by a specific time, useful in timing adjustments.

25. **Voltage-Controlled Current Source with Cascode**
    - **Description:** An enhanced current source using a cascode configuration for improved output resistance and performance.

26. **Programmable Gain Amplifier**
    - **Description:** Adjusts gain through MOSFET switches that select different feedback paths in an amplifier circuit.

27. **Constant-Gm Bias Circuit**
    - **Description:** Maintains constant transconductance over temperature and process variations using MOSFETs in feedback configurations.

28. **Comparator with Hysteresis**
    - **Description:** Uses a differential pair and positive feedback through MOSFETs to introduce hysteresis, preventing false triggering from noise.

29. **3-bit Ripple Carry Adder**
    - **Description:** Chains multiple full adders (each implemented with CMOS logic) to add multi-bit binary numbers.

30. **Dual Slope Integrator**
    - **Description:** Integrates an input signal over time using a MOSFET-based switch and capacitor, commonly used in precise ADCs.

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### **Hard Level (25-45 Transistors)**

1.  **8-Bit Shift Register**

**Description:** An 8-bit shift register is a sequence of eight D flip-flops connected in series. Each flip-flop shifts a data bit to the next one on each clock pulse, moving data from the input to the output bit-by-bit. This arrangement allows for serial data transfer and storage, controlled by a common clock signal.


2. 4-bit Synchronous Binary Counter in CMOS

**Description**: This 4-bit synchronous binary counter uses D-type flip-flops and CMOS-based logic gates to create a counter that progresses in a binary sequence. The design is synchronous, meaning that all flip-flops receive a common clock signal, ensuring simultaneous updates and eliminating ripple delays typically found in asynchronous designs. Each of the four flip-flops (FF0 to FF3) represents one bit of the counter's output, moving from the least significant bit to the most significant. The first flip-flop (FF0) toggles on each clock pulse, while the subsequent flip-flops toggle based on the outputs of preceding flip-flops, managed by additional logic gates. 

The input for each flip-flop, D0 to D3, is set based on an AND gate arrangement: FF0 toggles on each clock pulse; FF1 toggles when FF0 is high; FF2 toggles when both FF0 and FF1 are high, and FF3 toggles when FF0, FF1, and FF2 are high. To achieve the AND gate functionality in CMOS, a combination of NAND gates and inverters is used, creating robust synchronous control. Outputs from each flip-flop—Q0, Q1, Q2, and Q3—form the counter’s 4-bit binary output, counting sequentially from 0 to 15. This CMOS-based 4-bit counter is compact and efficient, demonstrating stable synchronous counting suitable for digital applications.



3.  **Operational Amplifier (Op-Amp)**
   - **Description:** A multi-stage amplifier including differential input stage, gain stage, and output stage, using MOSFETs throughout.

4. Phase-Locked Loop (PLL) Circuit in MOSFET Technology

**Description**: This Phase-Locked Loop (PLL) circuit synchronizes an output oscillator with an external reference signal, achieving phase alignment and frequency control. It consists of three key components: a phase detector, a voltage-controlled oscillator (VCO), and a loop filter, all implemented using MOSFET technology for precise control and stability.

The phase detector compares the phase of the input reference signal with the output of the VCO. Any phase difference generates an error signal, which indicates whether the VCO should speed up or slow down. This error signal then passes through a loop filter, which smooths out rapid changes, generating a stable control voltage for the VCO. The voltage-controlled oscillator adjusts its frequency based on this control voltage, gradually aligning its phase with the reference signal. 

In this MOSFET-based design, each component is optimized for integration and low-power operation. The phase detector uses MOSFETs configured to produce an accurate and fast response to phase differences. The loop filter, also realized with MOSFETs, ensures a stable and low-noise control voltage, while the VCO adjusts the output frequency in response to minor fluctuations in the control voltage, thereby locking onto the reference signal. This PLL circuit provides reliable phase synchronization suitable for applications in communication systems, frequency synthesis, and signal processing.


5. **Analog Multiplier**
   - **Description:** Multiplies two analog signals using MOSFET transconductance properties, often implemented with differential pairs.

6. **8-bit Multiplexer**
   - **Description:** Selects one of eight inputs using select lines. Requires more transmission gates and logic gates compared to a 4:1 MUX.

7. **Delta-Sigma Modulator**
   - **Description:** Oversamples and noise-shapes an input signal for high-resolution ADCs, using integrators and comparators made with MOSFETs.

8. **Successive Approximation Register (SAR) ADC**
   - **Description:** Converts analog signals to digital by approximating each bit. Uses a DAC, comparator, and control logic, all implemented with MOSFETs.

9. **High-Frequency Oscillator**
   - **Description:** Generates high-frequency signals using LC tanks and MOSFET amplifiers, requiring careful transistor layout for performance.

10. **Bandgap Voltage Reference with Temperature Compensation**
    - **Description:** An improved voltage reference circuit that compensates for temperature variations using additional transistors and diodes.

11. **Instrumentation Amplifier**
    - **Description:** Amplifies small differential signals with high common-mode rejection. Uses multiple op-amp stages built with MOSFETs.

12. **4-bit Arithmetic Logic Unit (ALU)**
    - **Description:** Performs arithmetic and logic operations. Combines adders, logic gates, and multiplexers in CMOS logic.

13. **Low-Noise Amplifier (LNA)**
    - **Description:** Amplifies weak signals with minimal added noise. Uses MOSFETs biased in optimal regions and noise-matching techniques.

14. **Voltage-Controlled Filter**
    - **Description:** Adjusts filter characteristics based on a control voltage using MOSFETs as variable resistors in filter networks.

15. **Quadrature Oscillator**
    - **Description:** Generates two sinusoidal outputs 90 degrees out of phase. Uses integrator and inverter stages with MOSFETs.

16. **Transimpedance Amplifier**
    - **Description:** Converts input current to output voltage. Commonly used with photodiodes, implemented with MOSFET-based op-amps.

17. **Switched-Capacitor Filter**
    - **Description:** Uses MOSFET switches and capacitors to emulate resistors, allowing precise filter characteristics in integrated circuits.

18. **4-bit Ripple Carry Multiplier**
    - **Description:** Multiplies two 4-bit numbers using an array of adders and logic gates, realized with CMOS transistors.

19. **Charge Pump Phase-Locked Loop**
    - **Description:** A PLL that uses a charge pump circuit (with MOSFET switches) to adjust the control voltage for the VCO.

20. **Voltage Regulator with Overcurrent Protection**
    - **Description:** Includes sensing and control circuits to protect against overcurrent conditions, using additional MOSFETs for sensing.

21. **Digital-to-Analog Converter (DAC)**
    - **Description:** Converts digital codes to analog voltages using current steering or R-2R ladder networks implemented with MOSFETs.

22. **Gilbert Cell Mixer with Gain Control**
    - **Description:** An RF mixer that includes additional transistors to adjust gain, improving performance in communication systems.

23. **Temperature Sensor Circuit**
    - **Description:** Outputs a voltage or current proportional to temperature. Uses MOSFETs with known temperature characteristics.

24. **Logarithmic Amplifier**
    - **Description:** Provides an output proportional to the logarithm of the input signal, using the exponential characteristics of MOSFETs.

25. **Exponential Current Source**
    - **Description:** Generates a current that is an exponential function of the input voltage, useful in function generators.

26. **Voltage-to-Frequency Converter**
    - **Description:** Converts input voltage levels into proportional frequency outputs using oscillators and voltage-controlled elements.

27. **8-bit Johnson Counter**
    - **Description:** A twisted ring counter using flip-flops to cycle through a sequence of states, implemented with CMOS transistors.

28. **Analog Phase Shifter**
    - **Description:** Shifts the phase of an analog signal using all-pass filter configurations with MOSFETs.

29. **PLL Frequency Synthesizer**
    - **Description:** Generates multiple frequencies from a single reference frequency using a complex PLL architecture with frequency dividers.

30. **Adaptive Biasing Circuit**
    - **Description:** Adjusts bias currents dynamically to optimize performance over process and temperature variations, using feedback networks.

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### **Extreme Level (>45 Transistors)**

1. **16-bit Microprocessor Core (Simplified)**
   - **Description:** A simplified processor including an ALU, registers, and control logic. Implemented with extensive CMOS logic circuits.

2. **Sigma-Delta ADC**
   - **Description:** A high-resolution ADC using oversampling and noise shaping, comprising integrators, comparators, and digital filters with numerous MOSFETs.

3. **High-Resolution DAC**
   - **Description:** Converts high-bit-depth digital signals to analog voltages. Uses complex current steering or segmented architectures.

4. **Frequency Synthesizer with Phase Noise Optimization**
   - **Description:** A PLL-based circuit designed to minimize phase noise, involving intricate loop filter designs and high-performance VCOs.

5. **High-Frequency PLL with Loop Filters**
   - **Description:** A PLL operating at high frequencies, requiring precise MOSFET implementations in the VCO and phase detector.

6. **Integrated Voltage Regulator with Multiple Outputs**
   - **Description:** Manages several regulated outputs with load regulation and protection features, using multiple control loops and power MOSFETs.

7. **Digital Signal Processor (DSP) Core (Simplified)**
   - **Description:** Performs complex mathematical operations on digital signals. Includes multipliers, adders, and accumulators implemented with CMOS logic.

8. **Serializer/Deserializer (SerDes)**
   - **Description:** Converts parallel data to serial form and vice versa for high-speed communication, involving complex timing and control circuits.

9. **16-bit ALU**
   - **Description:** An arithmetic logic unit capable of handling 16-bit operations, requiring extensive use of CMOS gates and multiplexers.

10. **Pipeline ADC**
    - **Description:** A high-speed ADC that processes data through multiple stages (pipelines), each with its own comparators and amplifiers.

11. **Switched-Capacitor Sigma-Delta Modulator**
    - **Description:** A modulator for high-resolution ADCs using switched-capacitor techniques, involving precise timing control with MOSFET switches.

12. **Image Sensor Readout Circuit**
    - **Description:** Interfaces with pixel arrays to read and process image data, using amplifiers and multiplexers.

13. **Multi-Stage Operational Amplifier with Compensation**
    - **Description:** An op-amp with several gain stages and frequency compensation networks to ensure stability over various conditions.

14. **Class D Audio Amplifier**
    - **Description:** Uses MOSFETs as switches in a PWM configuration to achieve high-efficiency audio amplification.

15. **Digital Filter Implementation**
    - **Description:** Realizes filters like FIR or IIR using digital logic blocks and registers built from CMOS transistors.

16. **RF Power Amplifier**
    - **Description:** Amplifies radio frequency signals with high output power, involving matching networks and linearization circuits.

17. **Neural Network Hardware Accelerator (Simplified)**
    - **Description:** Implements neural network computations in hardware using arrays of multipliers and adders.

18. **Flash Memory Cell Array**
    - **Description:** Stores data using floating-gate MOSFETs arranged in a grid, involving numerous transistors for storage and control.

19. **LCD Driver Circuit**
    - **Description:** Drives the pixels of an LCD display by controlling voltages across liquid crystals, using shift registers and level shifters.

20. **Data Encryption Circuit (e.g., AES)**
    - **Description:** Hardware implementation of encryption algorithms requiring complex combinational and sequential logic circuits.

21. **Switched-Mode Power Supply Controller**
    - **Description:** Controls MOSFET switches to regulate output voltage in a switched-mode power supply, involving PWM generation and feedback loops.

22. **32-bit Shift Register**
    - **Description:** A large shift register for data storage, involving many flip-flops and control logic.

23. **Phased Array Antenna Beamforming Circuit**
    - **Description:** Adjusts the phase and amplitude of signals across multiple antennas using complex analog and digital circuits.

24. **High-Speed Serializer**
    - **Description:** Converts parallel data into high-speed serial data streams, requiring precise timing and signal integrity management.

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