PSA2001
Low-offset precision op-amp with 10uV offset, rail-to-rail I/O, 2MHz bandwidth for sensor applications
Product Overview
Description
The PSA2001 is a precision operational amplifier featuring ultra-low offset voltage of 10uV and rail-to-rail input and output operation.
With low noise of 15nV/√Hz and 2MHz bandwidth, this amplifier is ideal for sensor signal conditioning and precision measurement applications.
The device operates from single or dual supplies, features low input bias current of 50pA, and excellent stability with capacitive loads.
Product Series
PSA
Primary Application
Sensor signal conditioning
Key Features
- Ultra-low offset voltage: 10uV max
- Low offset drift: 0.05uV/°C
- Rail-to-rail input and output
- Low noise: 15nV/√Hz
- Low input bias current: 50pA
- High CMRR: 120dB
- High PSRR: 110dB
- Stable with capacitive loads
- Single or dual supply operation
Specifications
| Offset Voltage | 10uV max |
|---|---|
| Offset Drift | 0.05uV/°C |
| Input Bias Current | 50pA typical |
| Noise Density | 15nV/√Hz @ 1kHz |
| Bandwidth | 2MHz |
| Slew Rate | 1.5V/us |
| CMRR | 120dB |
| PSRR | 110dB |
| Supply Voltage | 2.7V - 5.5V single, ±1.35V - ±2.75V dual |
| Temperature Range | -40°C to +85°C (Industrial), -40°C to +125°C (Automotive) |
| Package | SOT-23-5, SOIC-8, MSOP-8 |
Applications
Sensor signal conditioning
Sensor signal conditioning
Precision data acquisition
Data acquisition and conversion
Active filters
Electronic system design
Buffer amplifiers
Electronic system design
Medical instrumentation
Medical electronics
Test and measurement
Data acquisition and conversion
Battery-powered equipment
Battery and charging management
FAE Expert Insights
"The PSA2001 is my top choice for precision sensor applications. The 10uV offset voltage is exceptional for a general-purpose op-amp, eliminating the need for external trimming in many applications. I've used this amplifier in thermocouple measurement circuits where the low offset drift of 0.05uV/°C ensures stable readings across temperature. The rail-to-rail input is particularly useful for single-supply sensor applications where the input can approach the supply rails. The low bias current of 50pA makes it suitable for high-impedance sensors like pH electrodes. For best DC performance, I recommend using a solid ground plane and keeping input traces short and symmetric."
Ultra-low offset with rail-to-rail operation for precision sensors
— Lisa Chen, BeiLuo
Frequently Asked Questions
What is the input offset voltage and why is it important?
Input offset voltage is the differential voltage that must be applied to the input terminals to force the output to zero. The PSA2001 has a maximum offset of 10uV, which is excellent for precision applications. Offset voltage is important because it directly affects DC accuracy - for a gain of 100, a 10uV offset becomes 1mV at the output. This error adds to the sensor signal and cannot be distinguished from real data. Low offset is critical for sensors with small output signals like thermocouples (40uV/°C) and strain gauges (2mV/V).
Select amplifiers with offset voltage less than 1% of your minimum signal. The PSA2001 is excellent for millivolt-level signals.
How does the rail-to-rail input stage work?
Rail-to-rail input allows the amplifier to accept input voltages that extend to or beyond the power supply rails. The PSA2001 uses a complementary input stage with both PMOS and NMOS transistors. The PMOS pair operates near the negative rail, while the NMOS pair operates near the positive rail. This provides continuous operation across the entire supply range. Rail-to-rail input is essential for single-supply applications where the sensor output may approach ground or the positive supply, such as bridge sensors powered from the same supply as the amplifier.
Use rail-to-rail input amplifiers for single-supply sensor applications. The PSA2001 handles inputs to both supply rails.
What is the significance of input bias current?
Input bias current is the small current that flows into or out of the amplifier input terminals due to the base or gate current of the input transistors. The PSA2001 has a very low bias current of 50pA, making it suitable for high-impedance sources. Bias current flowing through source resistance creates an offset voltage (V_error = I_bias × R_source). For a 1MΩ source resistance, 50pA bias current creates only 50uV error. High bias current can also cause errors when charging input capacitance, affecting settling time in multiplexed systems.
Select amplifiers with bias current at least 100x lower than your signal current. The PSA2001 is excellent for high-impedance sensors.
How do I compensate for offset voltage in critical applications?
For applications requiring offset compensation: 1) Use chopper-stabilized or auto-zero amplifiers for lowest offset; 2) Implement software calibration by measuring offset with known zero input and subtracting from readings; 3) Use AC coupling with high-pass filtering for applications where DC information is not needed; 4) Implement hardware trimming using potentiometer or digital potentiometer; 5) Use differential measurement with reference channel to cancel common errors. The PSA2001's low intrinsic offset often eliminates the need for external compensation.
The PSA2001's 10uV offset is sufficient for most applications. For ultra-precision, consider software calibration or chopper amplifiers.
What is the gain bandwidth product and how does it affect my circuit?
Gain bandwidth product (GBW) is the frequency at which the amplifier's open-loop gain drops to unity. For the PSA2001 with 2MHz GBW, the available bandwidth at a closed-loop gain of 10 is 200kHz (2MHz/10). Higher gain results in lower bandwidth. GBW determines the maximum frequency that can be amplified at a given gain. For sensor applications, ensure the amplifier bandwidth exceeds the signal bandwidth by at least 5-10x for flat frequency response. The PSA2001's 2MHz GBW supports gains up to 100 for 20kHz signals.
Calculate required GBW based on signal bandwidth and gain. The PSA2001 supports gains up to 100 for audio-frequency signals.