CA3130 — 15MHz BiMOS Operational Amplifier with MOSFET Input & CMOS Output

Overview

The CA3130 (CA3130A / CA3130E) is an iconic 15MHz BiMOS operational amplifier manufactured by Renesas Electronics (originally developed by RCA and Intersil). Available in an 8-pin through-hole DIP-8 and TO-5 metal can package, it combines gate-protected PMOS field-effect transistors in the input stage with a CMOS output stage capable of swinging rail-to-rail.

Operating from $5.0\text{V}$ to $16.0\text{V}$ DC (or $\pm 2.5\text{V} \dots \pm 8.0\text{V}$ split rails), the CA3130 boasts an ultra-high input impedance of $1.5\ \text{T}\Omega$ ( $1.5 \times 10^{12}\ \Omega$ ), an extremely low input bias current of $5\text{ pA}$ , a wide gain-bandwidth product of $15\text{ MHz}$ , and a rapid slew rate of $30\text{ V}/\mu\text{s}$ . Because its CMOS output stage swings within millivolts of ground and the positive supply rail, the CA3130 has been a legendary staple in analog modular synthesizers (VCO core reset circuits, sample-and-hold buffers), electrometer preamplifiers, pH meter probes, and ultra-high-impedance touch switches.

Quick reference


Amplifier Type	BiMOS (MOSFET Input, CMOS Rail-to-Rail Output)
Channels	1 (Single Op-Amp)
Package	8-pin DIP (DIP-8 / PDIP-8) / 8-pin SOIC / TO-5 Metal Can
Supply Voltage Range ( $V^+ - V^-$ )	$5.0\text{ V}$ to $16.0\text{ V}$ (Single Supply: $+5\text{V} \dots +16\text{V}$ , Dual: $\pm 2.5\text{V} \dots \pm 8\text{V}$ )
Input Impedance ( $R_{IN}$ )	$1.5\ \text{T}\Omega$ ( $1.5 \times 10^{12}\ \Omega$ )
Input Bias Current ( $I_B$ )	$5\text{ pA}$ typical ( $15\text{ pA}$ max on CA3130A)
Gain-Bandwidth Product (GBW)	$15\text{ MHz}$
Slew Rate ( $SR$ )	$30\text{ V}/\mu\text{s}$ (uncompensated) / $10\text{ V}/\mu\text{s}$ (compensated)
Output Voltage Swing	True Rail-to-Rail ( $10\text{ mV}$ from $V^+$ and $V^-$ with $100\text{ k}\Omega$ load)
Strobe Terminal	Pin 8 allows digital shutdown/strobing of output stage

Pinout (DIP-8 Package)

text

                            ┌───┴───┐
            OFFSET NULL  1│ 1   8 │ STROBE / COMPENSATION
       (Inverting -IN)   2│ CA3130│ 7 V+ (Positive Supply)
   (Non-Inverting +IN)   3│ DIP-8 │ 6 OUTPUT (CMOS Rail-to-Rail)
       (Negative V-)     4│       │ 5 OFFSET NULL
                            └───────┘

Pin	Name	Type	Description
1	`OFFSET NULL`	Input	Offset voltage nulling / Phase compensation connection
2	`INV. INPUT`	Analog Input	Inverting Op-Amp Input terminal (`-IN`)
3	`NON-INV. INPUT`	Analog Input	Non-Inverting Op-Amp Input terminal (`+IN`)
4	`V- / GND`	Power	Negative Supply Rail (or Ground for single-supply operation)
5	`OFFSET NULL`	Input	Offset voltage nulling terminal
6	`OUTPUT`	Analog Output	CMOS Rail-to-Rail Output
7	`V+`	Power	Positive Supply Rail ( $+5.0\text{ V}$ to $+16.0\text{ V}$ )
8	`STROBE / COMP`	Control/Input	Strobe (pull LOW to disable output) / Phase compensation capacitor

Specifications

Parameter	Symbol	Min	Typ	Max	Unit	Conditions
Input Offset Voltage	$V_{OS}$	—	8.0	15.0	mV	CA3130 (2.0mV typ on CA3130A)
Input Bias Current	$I_B$	—	5.0	50.0	pA	$T_A = 25^\circ\text{C}, V^+ = 15\text{V}$
Input Resistance	$R_{IN}$	—	1.5	—	TΩ	$T_A = 25^\circ\text{C}$
Large-Signal Voltage Gain	$A_{VOL}$	32000	320000	—	V/V	$110\text{ dB}$ with $R_L = 2\text{ k}\Omega$
Slew Rate	$SR$	—	30	—	V/µs	Uncompensated, $R_L = 2\text{ k}\Omega$
Gain-Bandwidth Product	$GBW$	—	15	—	MHz	$f = 1\text{ MHz}$
Supply Current	$I_{CC}$	—	10.0	15.0	mA	$V^+ = 15\text{V}, I_O = 0$

Typical Application Circuit: High-Impedance Electrometer Buffer

text

                            +12V to +15V Single Supply
                                  │
                           [Pin 7: V+]
                                  │
     High-Z Signal In             │
     (pH probe / Piezo)           │
           │                      │
           └───► [Pin 3: +IN]     │
                  CA3130E         ├────► [Pin 6: OUTPUT] ─── Low-Z Buffered Output
           ┌───► [Pin 2: -IN] ────┘
           │
           │      [Pin 4: V-]
           │          │
           └──────────┴──────────────── Common GND
           
  Phase Compensation (Required for Unity-Gain Stability):
    Pin 1 ───[ 47pF - 56pF Ceramic Cap ]─── Pin 8

Common mistakes

Omitting the unity-gain phase compensation capacitor: The CA3130 is not internally unity-gain compensated. When wired as a voltage follower ( $A_V = 1$ ) or low-gain amplifier, it will oscillate violently unless a $47\text{ pF} \dots 56\text{ pF}$ ceramic capacitor is placed directly between Pin 1 and Pin 8. (For an internally compensated alternative with bipolar output, use the CA3140).
Exceeding the 16V supply rating: Unlike standard 36V op-amps (LM741, TL072), the CA3130's maximum supply voltage rating is $16.0\text{V}$ total ( $+16\text{V}$ single or $\pm 8\text{V}$ split). Connecting $\pm 15\text{V}$ rails will instantly destroy the CMOS output transistors.

Notes

CA3130 vs CA3140: CA3130 features a rail-to-rail CMOS output stage ( $15\text{MHz}$ , uncompensated, 16V max); CA3140 features a Class AB Bipolar output stage ( $4.5\text{MHz}$ , internally unity-gain compensated, 36V max).

Interface	8-Pin Analog (Inputs, Output, Offset Null, Strobe)
Supply	5.0 (Single Supply) / ±2.5 (Dual Supply)–16.0 (Single Supply) / ±8.0 (Dual Supply) V
Package	8-pin DIP (DIP-8 / PDIP-8) / 8-pin SOIC / 8-pin TO-5 Metal Can