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You aim to design a topology for a given circuit described in the text. Please ensure your designed circuit topology works properly and achieves the design requirements.

Here is an example:

Question

Design a 2-stage amplifier (first stage: a common-source stage with current-source load, second stage: a common-source stage with resistor load).

Input node name: Vin, Vbias.

Output node name: Vout.

Answer

Task 1

Components Needed

  • NMOS Transistors: M1 and M3
  • PMOS Transistors: M2 (used as the current source in the first stage)
  • Resistors: R1 for the second stage load
  • Power Supply: Vdd for DC supply
  • Input Signal Source: Vin, Vbias for biasing and signal input
  • Capacitors: Not specified but can be included for coupling and bypass applications if required

Stage 1: Common-Source Amplifier with Current Source Load

  1. Transistor Setup:

    • M1 (NMOS) as the main amplifying transistor.
    • Gate of M1 is connected to the input node Vin.
    • Source of M1 connected to the ground.
    • Drain of M1 connected to the drain of M2.

  2. Biasing:

    • Vin provides the input signal.
    • Vbias is used to bias M2 (PMOS), ensuring it operates as a current source.

  3. Current Source Load (M2):

    • M2, a PMOS transistor, is configured as a current source.
    • The source of M2 is connected to Vdd, and its gate is connected to Vbias.
    • Drain of M2 is connected to the drain of M1, providing a high-impedance load.

Stage 2: Common-Source Amplifier with Resistor Load

  1. Transistor Setup:

    • M3 (NMOS) as the main amplifying transistor for the second stage.
    • Gate of M3 connected to the drain of M1.
    • Source of M3 connected to the ground.
    • Drain of M3 connected to Vout through resistor R1.

  2. Load and Coupling:

    • R1 connects the drain of M3 to Vdd. This resistor converts the current through M3 into an output voltage.

Task 2

from PySpice.Spice.Netlist import Circuit
from PySpice.Unit import *

circuit = Circuit('Two-Stage Amplifier')
# Define the MOSFET models
circuit.model('nmos_model', 'nmos', level=1, kp=100e-6, vto=0.5)
circuit.model('pmos_model', 'pmos', level=1, kp=50e-6, vto=-0.5)

# Power Supplies for the power and input signal

circuit.V('dd', 'Vdd', circuit.gnd, 5.0) # 5V power supply
circuit.V('in', 'Vin', circuit.gnd, 1.0) # 1V input for bias voltage (= V_th + 0.5 = 0.5 + 0.5 = 1.0)
circuit.V('bias', 'Vbias', circuit.gnd, 4.0) # 4V input for bias voltage (= Vdd - |V_th| - 0.5 = 5.0 - 0.5 - 0.5 = 4.0)

# First Stage: Common-Source with Active Load
# parameters: name, drain, gate, source, bulk, model, w, l
circuit.MOSFET('1', 'Drain1', 'Vin', circuit.gnd, circuit.gnd, model='nmos_model', w=50e-6, l=1e-6)
circuit.MOSFET('2', 'Drain1', 'Vbias', 'Vdd', 'Vdd', model='pmos_model', w=100e-6, l=1e-6)

# Second Stage: Common-Source with Resistor Load
circuit.MOSFET('3', 'Vout', 'Drain1', circuit.gnd, circuit.gnd, model='nmos_model', w=100e-6, l=1e-6)
circuit.R('1', 'Vout', 'Vdd', 1@u_kΩ)

# Analysis Part
simulator = circuit.simulator()

As you have seen, the output of your designed topology should consist of two tasks:

  1. Give a detailed design plan about all devices and their interconnectivity nodes and properties.
  2. Write a complete Python code, describing the topology of integrated analog circuits according to the design plan.

Please make sure your Python code is compatible with PySpice. Please give the runnable code without any placeholders.

Do not write other redundant codes after simulator = circuit.simulator().

There are some tips you should remember all the time:

  1. For the MOSFET definition circuit.MOSFET(name, drain, gate, source, bulk, model, w=w1,l=l1), be careful about the parameter sequence.
  2. You should connect the bulk of a MOSFET to its source.
  3. Please use the MOSFET threshold voltage, when setting the bias voltage.
  4. Avoid giving any AC voltage in the sources, just consider the operating points.
  5. Make sure the input and output node names appear in the circuit.
  6. Avoid using subcircuits.
  7. Use nominal transistor sizing.
  8. Assume the Vdd = 5.0 V.

Question

Design [TASK].

Input node name: [INPUT].

Output node name: [OUTPUT].

Answer