OP_PGA.CIR - PROGRAMMABLE GAIN AMPLIFIER * * INPUT PULSES, ONE FOR EACH GAIN SETTING VSIG 1 0 PULSE(0V 1V 2.5US 0.01US 0.01US 5US 10US) * * PGA 1 XOP1 1 2 3 OPAMP1 * S0 3 2 20 0 SW1 * R1 3 4 2K S1 4 2 21 0 SW1 R2 4 5 1K S2 5 2 22 0 SW1 R3 5 6 500 S3 6 2 23 0 SW1 R4 6 0 500 * * * PGA 2 XOP2 1 7 8 OPAMP1 * R11 8 7 2K * R12 7 9 1.9K S12 9 0 21 0 SW1 R13 7 10 566.7 S13 10 0 22 0 SW1 R14 7 11 185.7 S14 11 0 23 0 SW1 * * * SWITCH CONTROL VS0 20 0 PULSE(0V 5V 0US 0.1US 0.1US 10US 40US) RS0 20 0 1MEG VS1 21 0 PULSE(0V 5V 10US 0.1US 0.1US 10US 40US) RS1 21 0 1MEG VS2 22 0 PULSE(0V 5V 20US 0.1US 0.1US 10US 40US) RS2 22 0 1MEG VS3 23 0 PULSE(0V 5V 30US 0.1US 0.1US 10US 40US) RS3 23 0 1MEG * .MODEL SW1 VSWITCH(VON=5V VOFF=0V RON=100 ROFF=100MEG) * * * OPAMP MACRO MODEL, SINGLE-POLE * connections: non-inverting input * | inverting input * | | output * | | | .SUBCKT OPAMP1 1 2 6 * INPUT IMPEDANCE RIN 1 2 10MEG * DC GAIN=100K AND POLE1=100HZ * UNITY GAIN = DCGAIN X POLE1 = 10MHZ EGAIN 3 0 1 2 100K RP1 3 4 100K CP1 4 0 0.0159UF * OUTPUT BUFFER AND RESISTANCE EBUFFER 5 0 4 0 1 ROUT 5 6 10 * .ENDS * * ANALYSIS .TRAN 0.5US 40US * * VIEW RESULTS .PRINT TRAN V(3) V(1) .PROBE .END