```spice
* Enhanced PGA PSPICE Model
.SUBCKT PGA IN+ IN- CTRL OUT+ OUT- VDD VSS
* Parameters
.PARAM TEMP_NOM = 27     ; Nominal temperature in celsius
.PARAM VOS = 2E-3        ; Input offset voltage
.PARAM CMRR = 10000     ; Common Mode Rejection Ratio
.PARAM PSRR = 30000    ; Power Supply Rejection Ratio
.PARAM SR = 10E6         ; Slew Rate (V/s)
.PARAM GBW = 7E6        ; Gain-Bandwidth product
.PARAM VNOISE = 100E-9    ; Input voltage noise density (V/√Hz)

* Input Stage with Common Mode Rejection
* Common mode voltage calculation
E_CM CM 0 VALUE = {(V(IN+) + V(IN-))/2}
* Differential input with offset and CMRR
E_IN INDIFF 0 VALUE = {V(IN+,IN-) + VOS + V(CM)/CMRR}

* Power Supply Rejection
E_PSR PSR 0 VALUE = {(V(VDD) - V(VSS))/PSRR}

* Gain Control Stage
.PARAM GAIN = {
+ IF(V(CTRL) < 1, 1,    
+ IF(V(CTRL) < 2, 2,    
+ IF(V(CTRL) < 3, 4,    
+ IF(V(CTRL) < 4, 8,
+ IF(V(CTRL) < 5, 16,
+ IF(V(CTRL) < 6, 32,
+ IF(V(CTRL) < 7, 64,
+ 20))))}

* Frequency Response and Slew Rate Limiting
* First order frequency response
EFREQ FR 0 INDIFF 0 LAPLACE = {GAIN/(1+s/(2*PI*GBW/GAIN))}

* Slew Rate Limiting
ESR SR 0 FR 0 SLEW = SR

* Temperature Effects
.PARAM TEMP_COEFF = 0E-6  ; Temperature coefficient (V/°C)
E_TEMP TEMP 0 VALUE = {(TEMP-TEMP_NOM)*TEMP_COEFF*V(SR)}

* Noise Sources
* Voltage noise
VN1 NOISE1 0 AC 1
RN1 NOISE1 0 1
HN1 VNOISE 0 VN1 0 {VNOISE}

* Output Stage
* Combine all effects
E_OUT OUT_INT 0 VALUE = {V(SR) + V(TEMP) + V(PSR) + V(VNOISE)}

* Output voltage limitations
E_LIMIT OUT+ OUT- VALUE = {
+ MIN(MAX(V(OUT_INT), V(VSS) + 0.1), 
+ V(VDD) - 0.1)}

* Output current limiting
.PARAM IMAX = 220uA       ; Maximum output current
G_OUT OUT+ OUT- VALUE = {
+ MIN(MAX(I(E_LIMIT), -IMAX), IMAX)}

* Input Protection
D1 IN+ VDD DIODE
D2 VSS IN+ DIODE
D3 IN- VDD DIODE
D4 VSS IN- DIODE

* Input impedance
RIN1 IN+ 0 10MEG
CIN1 IN+ 0 1pF
RIN2 IN- 0 10MEG
CIN2 IN- 0 1pF

* Output impedance
ROUT OUT+ OUT- 76m
COUT OUT+ OUT- 10pF

* Power Supply Pins
RPD VDD 0 100K
RPS VSS 0 100K

* Model for protection diodes
.MODEL DIODE D (IS=1E-14 RS=0.1)

.ENDS PGA