CA3140 — 4.5MHz BiMOS Operational Amplifier with MOSFET Input & Bipolar Output

Overview

The CA3140 (CA3140A / CA3140E) is an internally compensated 4.5MHz BiMOS operational amplifier manufactured by Renesas Electronics (originally developed by RCA and Intersil). Available in a standard 8-pin through-hole DIP-8 and TO-5 metal can package, it features the pinout and footprint of the historic 741 / LF356 op-amps.

Combining gate-protected PMOS field-effect transistors in the input stage with a rugged bipolar Class AB output stage, the CA3140 delivers an ultra-high input impedance of $1.5\ \text{T}\Omega$ ( $1.5 \times 10^{12}\ \Omega$ ), an extremely low input bias current of $10\text{ pA}$ , a slew rate of $9\text{ V}/\mu\text{s}$ , and internal unity-gain stability. Operating across an ultra-wide voltage range from $4.0\text{V}$ to $36.0\text{V}$ DC (or $\pm 2.0\text{V} \dots \pm 18.0\text{V}$ split rails), its input common-mode voltage range extends down to $0.5\text{V}$ below the negative supply rail, making it one of the premier op-amps for photodiode transimpedance amplifiers, smoke detector sensors, piezoelectric preamplifiers, and analog integrators.

Quick reference


Amplifier Type	BiMOS (MOSFET Input, Bipolar Output)
Channels	1 (Single Op-Amp)
Package	8-pin DIP (DIP-8 / PDIP-8) / 8-pin SOIC / TO-5 Metal Can
Supply Voltage Range ( $V^+ - V^-$ )	$4.0\text{ V}$ to $36.0\text{ V}$ (Single Supply: $+4\text{V} \dots +36\text{V}$ , Dual: $\pm 2\text{V} \dots \pm 18\text{V}$ )
Input Impedance ( $R_{IN}$ )	$1.5\ \text{T}\Omega$ ( $1.5 \times 10^{12}\ \Omega$ )
Input Bias Current ( $I_B$ )	$10\text{ pA}$ typical ( $40\text{ pA}$ max on CA3140A)
Input Common-Mode Range	Includes Negative Rail ( $V^- - 0.5\text{V}$ to $V^+ - 2.9\text{V}$ )
Gain-Bandwidth Product (GBW)	$4.5\text{ MHz}$
Slew Rate ( $SR$ )	$9\text{ V}/\mu\text{s}$
Internal Compensation	Internally compensated for unity-gain stability ( $A_V \ge 1$ )
Offset Nulling	Standard 741-compatible pinout (Pins 1 and 5)

Pinout (DIP-8 Package)

text

                            ┌───┴───┐
            OFFSET NULL  1│ 1   8 │ STROBE
       (Inverting -IN)   2│ CA3140│ 7 V+ (Positive Supply)
   (Non-Inverting +IN)   3│ DIP-8 │ 6 OUTPUT (Bipolar Class AB)
       (Negative V-)     4│       │ 5 OFFSET NULL
                            └───────┘

Pin	Name	Type	Description
1	`OFFSET NULL`	Input	Input offset voltage nulling terminal (Connect to $100\text{ k}\Omega$ trim pot)
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	Input offset voltage nulling terminal
6	`OUTPUT`	Analog Output	Bipolar Class AB Output
7	`V+`	Power	Positive Supply Rail ( $+4.0\text{ V}$ to $+36.0\text{ V}$ )
8	`STROBE`	Digital Input	Strobe terminal (pull LOW to disable output stage)

Specifications

Parameter	Symbol	Min	Typ	Max	Unit	Conditions
Input Offset Voltage	$V_{OS}$	—	5.0	15.0	mV	CA3140 (2.0mV typ on CA3140A)
Input Bias Current	$I_B$	—	10.0	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	$A_{VOL}$	20000	100000	—	V/V	$100\text{ dB}$ with $R_L = 2\text{ k}\Omega$
Slew Rate	$SR$	—	9.0	—	V/µs	$R_L = 2\text{ k}\Omega, C_L = 100\text{ pF}$
Gain-Bandwidth Product	$GBW$	—	4.5	—	MHz	$f = 1\text{ MHz}$
Supply Current	$I_{CC}$	—	4.0	6.0	mA	$V^+ = 15\text{V}, I_O = 0$

Typical Application Circuit: Photodiode Transimpedance Amplifier

text

                          +15V Single Supply
                                │
                         [Pin 7: V+]
                                │
     Photodiode                 │
         ┌───┤◄├───┐            │
         │         │            │
         │   [Pin 2: -IN] ──────┼───[ Feedback Resistor: 10MΩ ]───┐
         │       CA3140E        │                                 │
         │   [Pin 3: +IN]       ├─────────────────────────────────┴──► Output Voltage (V = I_photo * R_f)
         │         │            │
         └─────────┼────────────┤
                   │            │
              [Pin 4: V-] ──────┴── Common Ground (0V)

Comparison: CA3140 vs CA3130 vs TL071

Parameter	CA3140	CA3130	TL071
Input Technology	PMOS ( $1.5\text{ T}\Omega$ )	PMOS ( $1.5\text{ T}\Omega$ )	JFET ( $1\text{ T}\Omega$ )
Input Bias Current	$10\text{ pA}$	$5\text{ pA}$	$65\text{ pA}$
Output Stage	Bipolar Class AB	CMOS Rail-to-Rail	Bipolar Class AB
Max Supply Voltage	$36\text{ V}$ ( $\pm 18\text{V}$ )	$16\text{ V}$ ( $\pm 8\text{V}$ )	$36\text{ V}$ ( $\pm 18\text{V}$ )
Unity-Gain Stability	Internally Compensated	External Cap Required	Internally Compensated

Common mistakes

Expecting rail-to-rail positive output swing: Unlike the CA3130, the CA3140's output stage is bipolar. While its output swings down to within $0.13\text{V}$ of ground on a single supply, its positive swing is limited to approximately $V^+ - 2.0\text{V}$ under load.
Handling without ESD precautions: The gate-protected PMOS input transistors are rated for $400\text{V}$ ESD, but static charges from ungrounded workbenches can degrade the ultra-low picoamp input bias characteristics over time.

Notes

Suffix Guide: CA3140E designates through-hole 8-pin plastic DIP; CA3140T designates 8-pin TO-5 hermetic metal can; CA3140M designates 8-pin SOIC.

Interface	8-Pin Analog (Inputs, Output, Offset Null, Strobe)
Supply	4.0 (Single Supply) / ±2.0 (Dual Supply)–36.0 (Single Supply) / ±18.0 (Dual Supply) V
Package	8-pin DIP (DIP-8 / PDIP-8) / 8-pin SOIC / 8-pin TO-5 Metal Can