User:John R. Brews/Circuits

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Circuits

Miscellaneous

Miscellaneous

(PD) Diagram: John R. Brews Thermostatic control of house temperature     (PD) Diagram: John R. Brews Negative feedback as a model for homeostasis     (PD) Diagram: John R. Brews Feedback control to set system status at a set point     (PD) Diagram: John R. Brews Keeping a car at the speed limit using negative feedback

Current sources

Current sources

(CC) Image: John R. Brews Widlar current source using bipolar transistors     (CC) Image: John R. Brews Small-signal circuit for finding output resistance of the Widlar source     (CC) Image: John R. Brews Design trade-off between output resistance and output current in Widlar source     (PD) Image: John R. Brews A current mirror implemented with npn bipolar transistors using a resistor to set the reference current IREF; VCC = supply voltage.     (PD) Image: John R. Brews An n-channel MOSFET current mirror with a resistor to set the reference current     (PD) Image: John R. Brews Gain-boosted current mirror with op amp feedback to increase output resistance.     (PD) Image: John R. Brews MOSFET version of wide-swing current mirror; M1 and M2 are in active mode     (PD) Image: John R. Brews Operational-amplifier based current sink. Because the op amp is modeled as a nullor, op amp input variables are zero regardless of the values for its output variables.     (PD) Image: John R. Brews A digital inverter circuit using a bipolar transistor.     (PD) Image: John R. Brews Transfer characteristic of bipolar inverter showing modes.     Collector current vs. input voltage for a bipolar inverter with VCC=5V and RC=1kΩ.     (PD) Image: John R. Brews Input and output signals for bipolar inverter used as an amplifier.     (PD) Image: John R. Brews Two-port network with symbol definitions.     (PD) Image: John R. Brews Z-equivalent two port showing independent variables I1 and I2.     (PD) Image: John R. Brews Y-equivalent two port showing independent variables     (PD) Image: John R. Brews H-equivalent two-port showing independent variables     (PD) Image: John R. Brews G-equivalent two-port showing independent variables     (PD) Image: John R. Brews Block diagram for asymptotic gain model     (PD) Image: John R. Brews Possible signal-flow graph for the asymptotic gain model     (PD) Image: John R. Brews MOSFET transresistance feedback amplifier.     (PD) Image: John R. Brews Collector-to-base biased bipolar amplifier.     (PD) Image: John R. Brews Two-transistor feedback amplifier; any source impedance RS is lumped in with the base resistor RB.

Small-signal circuits

Small-signal circuits

(PD) Image: John R. Brews Small-signal circuit for pn-diode driven by a current signal represented as a Norton source.     (PD) Image: John R. Brews Bipolar current mirror with emitter resistors     (PD) Image: John R. Brews Small-signal circuit for bipolar current mirror     (PD) Image: John R. Brews Common base circuit with active load and current drive.     (PD) Image: John R. Brews Common-base amplifier with AC current source I1 as signal input     (PD) Image: John R. Brews Bipolar transistor with base grounded and signal applied to emitter.     (PD) Image: John R. Brews Common-base amplifier with AC voltage source V1 as signal input     (PD) Image: John R. Brews The result of applying Norton's theorem.     (PD) Image: John R. Brews Bipolar current buffer.     (PD) Image: John R. Brews Small-signal circuit to find output current.     (PD) Image: John R. Brews Small-signal circuit with test current iX to find Norton resistance.     (PD) Image: John R. Brews The result of applying Thévenin's theorem.     (PD) Image: John R. Brews Bipolar buffer.     (PD) Image: John R, Brews Small-signal circuit for voltage follower.     (PD) Image: John R. Brews Determination of the small-signal output resistance.     (PD) Image: John R. Brews Simplified, low-frequency hybrid-pi BJT model.     (PD) Image: John R. Brews Bipolar hybrid-pi model with parasitic capacitances.     (PD) Image: John R. Brews Simplified, low-frequency hybrid-pi BJT model.     (PD) Image: John R. Brews Bipolar hybrid-pi model with parasitic capacitances.     (PD) Image: John R. Brews Simplified, three-terminal MOSFET hybrid-pi model.     (PD) Image: John R. Brews Four-terminal small-signal MOSFET circuit.     (PD) Image: John R. Brews Miller effect: These two circuits are equivalent.     (PD) Image: John R. Brews Small-signal circuit for transresistance amplifier     (PD) Image: John R. Brews Small-signal circuit with return path broken and test current it driving amplifier at the break.     (PD) Image: John R. Brews Three small-signal schematics used to discuss the asymptotic gain model

Return ratio

Return ratio

(PD) Image: John R. Brews Left - small-signal circuit corresponding to bipolar amplifier; Center - inserting independent source and marking leads to be cut; Right - cutting the dependent source free and short-circuiting broken leads.

Amplifiers

Amplifiers

(PD) Image: John R. Brews Some terms used to describe step response in time domain.     (PD) Image: John R. Brews Ideal negative feedback model; open loop gain is AOL and feedback factor is β.     (PD) Image: John R. Brews Conjugate pole locations for step response of two-pole feedback amplifier.     (PD) Image: John R. Brews Step-response of a linear two-pole feedback amplifier.     (PD) Image: John R. Brews Step response for three values of time constant ratio.     (PD) Image: John R. Brews Bode gain plot to find phase margin of two-pole amplifier.     (PD) Image: John R. Brews The Bode plot for a first-order (one-pole) highpass filter     (PD) Image: John R. Brews The Bode plot for a first-order (one-pole) lowpass filter     (PD) Image: John R. Brews Bode magnitude plot for zero and for low-pass pole     (PD) Image: John R. Brews Bode phase plot for zero and for low-pass pole     (PD) Image: John R. Brews Bode magnitude plot for pole-zero combination; the location of the zero is ten times higher than in above figures     (PD) Image: John R. Brews Bode phase plot for pole-zero combination; the location of the zero is ten times higher than in above figures     (PD) Image: John R. Brews Gain of feedback amplifier AFB in dB and corresponding open-loop amplifier AOL.     (PD) Image: John R. Brews Phase of feedback amplifier °AFB in degrees and corresponding open-loop amplifier °AOL.     (PD) Image: John R. Brews Gain of feedback amplifier AFB in dB and corresponding open-loop amplifier AOL.     (PD) Image: John R. Brews Phase of feedback amplifier AFB in degrees and corresponding open-loop amplifier AOL.     (PD) Image: John R. Brews Operational amplifier with compensation capacitor CC between input and output to cause pole splitting.     (PD) Image: John R. Brews Operational amplifier with compensation capacitor transformed using Miller's theorem to replace the compensation capacitor with a Miller capacitor at the input and a frequency-dependent current source at the output.     (PD) Image: John R. Brews Idealized Bode plot for a two pole amplifier design.     (PD) Image: John R. Brews Miller capacitance at low frequencies CM (top) and compensation capacitor CC (bottom) as a function of gain