• 输入失调电压：±40µV（最大值）
• 输入失调电压温漂：0.35µV/°C（最大值）
• 低电源电流：±18V 下为 950µA
• 低输入偏置电流：2nA（最大值）
• 低输入偏置电流温漂：15pA/°C（最大值）
• 增益带宽积：9.2MHz
• 差分输出压摆率：15V/µs
• 低输入电压噪声：1kHz 时为 3.7nV/√Hz
• 低 THD + N：10kHz 时为 -120dB
• 宽输入和输出共模范围
• 宽单电源工作电压范围：3V 至 36V
• 低电源电流断电特性：< 20µA
• 过载功率限制
• 电流限制
• 封装：8 引脚 VSSOP，8 引脚 SOIC
• 温度范围：–40°C 至 +125°C

• 数据采集 (DAQ)
• 模拟输入模块
• 变电站自动化
• 半导体测试
• 实验室和现场仪表

THP210 是一款超低失调电压、低噪声、高电压、精密、全差分放大器，可轻松过滤和驱动全差分信号链。THP210 还可用于将单端源转换为高分辨率模数转换器 (ADC) 所需的差分输出。双极性超级 ß 输入专为实现出色的失调电压、低噪声和 THD 而设计，可在极低的静态电流和输入偏置电流下产生极低的噪声系数。该器件专为要求低失调电压和功耗以及高信噪比 (SNR) 的信号调节电路而设计。

THP210 具有高压电源功能，支持高达 ±18V 的电源电压。高压差分信号链可通过该功能提高裕量和动态范围，而无需为差分信号的每个极性添加单独的放大器。极低的电压和电流噪声使得 THP210 可用于高增益配置，而对信号保真度的影响微乎其微。

at V_VS = ±15 V, T_A = 25°C, V_VOCM = V_VICM = 0 V, R_F = 2 kΩ, R_L = 10 kΩ, gain = –1 V/V, and V_PD = V_VS+ (unless otherwise noted)

VS = ±1.5 V, N = 190, mean = –2.66 µV, std dev = 8.81 µV

Figure 6-1 Input Offset Voltage Histogram

VS = ±15 V

Figure 6-3 Input Offset Voltage Drift Histogram

VS = ±18 V, VOCM = 0 V

Figure 6-5 Output Common Mode Voltage Offset

Figure 6-7 Input Bias Current vs Supply Voltage

Figure 6-9 Current Noise vs Frequency

f = 1 kHz, VS = ±15 V

Figure 6-11 Total Harmonic Distortion + Noise vs Amplitude

VS = ±15 V, CL = 50 pF

Figure 6-13 Closed-Loop Gain vs Frequency

Figure 6-15 Common-Mode Rejection Ratio vs Temperature

Figure 6-17 Power-Supply Rejection Ratio vs Temperature

VS = ±15 V

Figure 6-19 Output Impedance vs Frequency

Figure 6-21 Quiescent Current vs Temperature

Figure 6-23 Input Offset Voltage vs
Input Common-Mode Voltage

AV = 1

Figure 6-25 Small-Signal Overshoot vs Capacitive Load

Figure 6-27 Small-Signal Step Response, Falling

Figure 6-29 Output Slew Rate vs Supply Voltage

Figure 6-31 Open-Loop Gain vs Ouput Delta From Supply

Figure 6-33 Large-Signal Step Response

Figure 6-35 Output Common-Mode Step Response, Falling

Figure 6-37 Power-Down Time ( PD Low to High)

Figure 6-39 Output Negative Overload Recovery

VS = ±15 V, N = 120, mean = –1.13 µV, std dev = 5.61 µV

Figure 6-2 Input Offset Voltage Histogram

VS = ±18 V, VOCM = floating

Figure 6-4 Output Common-Mode Offset Voltage

Figure 6-6 Input Bias Current vs Input Common-Mode Voltage

Figure 6-8 Input-Referred Voltage Noise vs Frequency

VOUT = 3 VRMS, VS = ±15 V

Figure 6-10 Total Harmonic Distortion + Noise vs Frequency

VS = ±15 V, CL = 50 pF

Figure 6-12 Open-Loop Gain vs Frequency

VS = ±15 V

Figure 6-14 Common-Mode Rejection Ratio vs Frequency

VS = ±15 V

Figure 6-16 Power-Supply Rejection Ratio vs Frequency

VS = ±15 V

Figure 6-18 Maximum Output Voltage vs Frequency

Figure 6-20 Quiescent Current vs Supply Voltage

Figure 6-22 Quiescent Current vs Power-Down Delta
From Supply Voltage

Figure 6-24 Output Voltage vs Output Current

AV = 10

Figure 6-26 Small-Signal Overshoot vs Capacitive Load

Figure 6-28 Small-Signal Step Response, Rising

Figure 6-30 Output Voltage vs Output Current

Figure 6-32 Short-Circuit Current vs Temperature

Figure 6-34 Output Common-Mode Step Response, Rising

Figure 6-36 Output Settling Time to ±0.01%

Figure 6-38 Power-Down Time ( PD High to Low)

Figure 6-40 Output Positive Overload Recovery

The THP210 is a fully differential amplifier (FDA) configuration that offers high dc precision, very low noise and harmonic distortion in a single, low-power amplifier. The FDA is a flexible device where the main aim is to provide a purely differential output signal centered on a user-configurable, common-mode voltage that is usually matched to the input common-mode voltage required by an analog-to-digital converter (ADC). The circuit used for characterization of the differential-to-differential performance is seen in Figure 7-1

Figure 7-1 Differential Source to a Differential Gain of a 1-V/V Test Circuit

A similar circuit is used for single-ended to differential measurements, as shown in Figure 7-2.

Figure 7-2 Single-ended Source to Differential Gain of 1-V/V Test Circuit

The characterization plots fix the R_F (R_F1 = R_F2) value at 2 kΩ, unless otherwise noted. This value can be adjusted to match the system design parameters with the following considerations in mind:

• The current required to drive RF from the peak output voltage to the input common-mode voltage add to the overall output load current. If the total current (current through R_F + current through R_L) exceeds the current limit conditions, the device enters a current limit, causing the output voltage to collapse.
• High feedback resistor values (R_F > 100 kΩ) interact with the amplifier input capacitance to create a zero in the feedback network. Compensation must be added to account for potential source of instability; see the TI Precision Labs FDA Stability Training for guidance on designing an appropriate compensation network.

The THP210 is a low-noise, low-distortion fully-differential amplifier (FDA) that features Texas Instrument's super-beta bipolar input devices. Super-beta input devices feature very low input bias current as compared to standard bipolar technology. The low input bias current and current noise makes the THP210 an excellent choice for high-performance applications that require low-noise, differential-signal processing without significant current consumption. This device is also designed for analog-to-digital input circuits that require low offset and low noise in a single fully-differential amplifier. The THP210 features high-voltage capability, which allows the device to be used in ±15-V supply circuits without any additional voltage clamping or regulators. Because this device is unity-gain stable, the device allows high-voltage input signals to be attenuated to the low-voltage ADC domain without requiring additional compensation techniques.

The THP210 is designed on a modern bipolar process that features TI's super-beta input transistors. Traditional bipolar transistors feature excellent voltage noise and offset drift, but suffer a tradeoff in high input bias current (I_B) and high input bias current noise. Super-beta transistors offer the benefits of low voltage noise and low offset drift with an order of magnitude reduction in input bias current and reduction in input bias current noise. For many filter circuits, input bias current noise can dominate in circuits where higher resistance input resistors are used. The THP210 enables a fully-differential, low-noise amplifier design without restrictions of low input resistance at a power level unmatched by traditional single-ended amplifiers.

The THP210 features a power-down circuit to disable the amplifier when a low-power mode is required by the system. In the power-down state, the amplifier outputs are in a high-impedance state, and the amplifier total quiescent current is reduced to less than 20 µA.

The THP210 offers considerable flexibility in the configuration and selection of resistor values. Low input bias current and bias current noise allows for larger gain resistor values with minimal impact to noise or offset, see Section 9.1.3 for more details.

The design starts with the selection of the feedback resistor value. The 2-kΩ feedback resistor value used for the characterization curves is a good compromise among power, noise, and phase margin considerations. With the feedback resistor values selected (and set equal on each side), the input resistors are set to obtain the desired gain, with input impedance also set with these input resistors. Differential I/O designs provide an input impedance that is the sum of the two input resistors. Single-ended input to differential output designs present a more complicated input impedance. Most characteristic curves implement the single-ended to differential design as the more challenging requirement over differential-to-differential I/O designs.

During overload or fault conditions, many bipolar-based amplifiers draw significant (three to five times) quiescent current if the output voltage is clipped (meaning the output voltage becomes limited by the negative or positive supply rail).

The primary cause for this condition is that common-emitter output stages can consume excessive base current (up to 100x) when overdriven into saturation. In addition, the overload condition causes the feedback to be broken, which causes the slew boost to be permanently on. Depending on the slew boost circuit, this increases the tail current up to 4x.

The THP210 has an intelligent overload detection scheme that eliminates this problem, meaning that there is virtually no additional current consumption in the case of an overload event, represented in Figure 8-1. The protection circuit continuously monitors both the input and output stages of the amplifier. Figure 8-1 shows a measurements of the overload power limit behavior. If a large input voltage step (referred to as ΔV_IN) is detected, the protection circuit checks for the presence of a rapid change in the voltage at the output (referred to as ΔV_O). If the output is not changing because the output is clipped at supply rail, the protection circuit disables the slew-boost circuit and limit the base current of the predriver to prevent output saturation. After the overload condition is removed, the amplifier rapidly recovers to normal operating condition. Figure 8-1 indicates that in case of an overloaded output the current consumption at the supply pins (referred to I_(VS+) and I_(VS–)) does not exceed the limitations, and quickly recovers as soon as the overload condition has been removed.

Figure 8-1 Supply Current Change With Overloaded Outputs

The stability of the amplifiers is of key importance when designing application circuits with fully differential amplifiers. This stability becomes especially important when driving capacitive loads, such as the input for successive-approximation-register (SAR) analog-to-digital converters (ADCs). A trade-off is made between the bandwidth of an amplifier and keeping power consumption low; in many cases, FDAs are not unity gain stable. Currently, many FDAs are primarily designed to support high-speed ADCs, and thus, are typically decompensated. This decompensation comes with the drawback that the noise performance degrades because of noise gain peaking. Additional components and compensation techniques are required to handle these challenges and prevent potential instability of the FDA. For detailed analysis of how stability is defined and affected, see TI Precision Labs – Fully Differential Amplifiers – FDA Stability and Simulating Phase Margin.

The THP210 is unity-gain stable; therefore, this device can be used in gain configurations with gains > 1, and also in attenuating configurations with gains < 1, without requiring compensation techniques and sacrificing dynamic performance. This device can be of prime use for applications that need to interface large input signals to the low-voltage ADC domain.