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The OPA656 device combines a very wideband, unity-gain stable, voltage-feedback operational amplifier with a FET-input stage to offer an ultra high dynamic-range amplifier for Analog-to-Digital Converter (ADC) buffering and transimpedance applications. Extremely low DC errors give good precision in optical applications.
The high unity-gain stable bandwidth and JFET input allows exceptional performance in high-speed, low-noise integrators.
The high input impedance and low bias current provided by the FET input is supported by the ultra-low 7-nV/√Hz input voltage noise to achieve a very low integrated noise in wideband photodiode transimpedance applications.
Broad transimpedance bandwidths are achievable given the OPA656 device’s high 230-MHz gain bandwidth product. As shown below, a –3-dB bandwidth of 1 MHz is provided even for a high 1-MΩ transimpedance gain from a 47-pF source capacitance.
This blog will introduce OPA656 systematically from its features, pinout to its specifications, applications, also including OPA656 datasheet and so much more.
The following figure is the diagram of OPA656 pinout.
D Package DBV Package 8-Pin SOIC Surface-Mount
DBV Package 5-Pin SOT-23
The following figure shows the noninverting gain of +2 V/V circuit used as the basis for most of the Typical Characteristics. Most of the curves were characterized using signal sources with 50-Ω driving impedance, and with measurement equipment presenting a 50-Ω load impedance.
Noninverting G = +2 V/V Specifications and Test Circuit
The circuit of the following figure shows the inverting gain of –1 V/V test circuit used for most of the inverting Typical Characteristics. In this case, an additional resistor RM is used to achieve the 50-Ω input impedance required by the test equipment using in characterization. This input impedance matching is optional in a circuit board environment where the OPA656 is used as an inverting amplifier at the output of a prior stage.
Inverting G = –1 V/V Specifications and Test Circuit
The OPA656 provides a very low input noise voltage while requiring a low 14-mA quiescent supply current. To take full advantage of this low input noise, careful attention to the other possible noise contributors is required. The following figure shows the operational amplifier noise analysis model with all the noise terms included. In this model, all the noise terms are taken to be noise voltage or current density terms in either nV/√Hz or pA/√Hz.
Operational Amplifier Noise Analysis Model
The high GBP and low input voltage and current noise for the OPA656 make it an ideal wideband transimpedance amplifier for moderate to high transimpedance gains.
Wideband, High-Sensitivity, Transimpedance Amplifier
The following diagram shows the OPA656 package.
OPA656 Package
| key | OPA656 |
| Architecture | FET Voltage FB |
| Number of Channels (#) | 1 |
| Total Supply Voltage (Min) (+5V=5, +/-5V=10) | 7 |
| Total Supply Voltage (Max) (+5V=5, +/-5V=10) | 13 |
| BW @ Acl (MHz) | 500 |
| Acl, min spec gain (V/V) | 1 |
| Slew Rate (Typ) (V/us) | 290 |
| Vn at Flatband (Typ) (nV/rtHz) | 7 |
| Iq per channel (Typ) (mA) | 14 |
| Vos (Offset Voltage @ 25C) (Max) (mV) | 0.6 |
| Rail-to-Rail | No |
| Additional Features | N/A |
| Rating | Catalog |
| Operating Temperature Range (C) | -40 to 85 |
| Package Group | SOIC SOT-23 |
| Approx. Price (US$) | 4.73 | 1ku |
| Package Size: mm2:W x L (PKG) | 5SOT-23: 8 mm2: 2.8 x 2.9(SOT-23) 8SOIC: 29 mm2: 6 x 4.9(SOIC) |
| CMRR (Typ) (dB) | 86 |
| Input Bias Current (Max) (pA) | 5 |
| Offset Drift (Typ) (uV/C) | 2 |
| GBW (Typ) (MHz) | 500 |
| Output Current (Typ) (mA) | 70 |
| 2nd Harmonic (dBc) | 71 |
| 3rd Harmonic (dBc) | 81 |
| @ MHz | 5 |
Texas Instruments Incorporated (TI) is a global semiconductor design and manufacturing company that develops analog ICs and embedded processors. By employing the world's brightest minds, TI creates innovations that shape the future of technology. TI is helping more than 100,000 customers transform the future, today.
You can download OPA656 datasheet from the link given below:
Note: Please check their parameters and pin configuration before replacing them in your circuit.
Originally, op-amps were so named because they were used to model the basic mathematical operations of addition, subtraction, integration, differentiation, etc. in electronic analog computers. In this sense a true operational amplifier is an ideal circuit element.
The equivalent circuit model of an op-amp is shown on Figure 2. The voltage Vi is the differential input voltage Vi = Vp −Vn . Ri is the input resistance of the device and Ro is the output resistance. The gain parameter A is called the open loop gain.
Operational amplifiers are linear devices that have all the properties required for nearly ideal DC amplification and are therefore used extensively in signal conditioning, filtering or to perform mathematical operations such as add, subtract, integration and differentiation.
Op amps can be classified into 3 main types based on the input/output voltage range: Dual Supply, Single Supply, and Rail-to-Rail.
An operational amplifier is an integrated circuit that can amplify weak electric signals. An operational amplifier has two input pins and one output pin. Its basic role is to amplify and output the voltage difference between the two input pins.
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