TSH350_07 STMICROELECTRONICS | Alldatasheet
Document overview
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- PDF pages: 22
Technical content
Features
■ Bandwidth: 550MHz in unity gain ■ Quiescent current: 4.1mA ■ Slew rate: 940V/μs ■ Input noise: 1.5nV/√ Hz ■ Distortion: SFDR=-66dBc (10MHz, 1Vpp) ■ 2.8Vpp minimum output swing on 100Ω load for a 5V supply ■ Tested on 5V power supply
Applications
■ Communication & video test equipment ■ Medical instrumentation ■ ADC drivers
Description
The TSH350 is a current feedback operational amplifier using a very high-speed complementary technology to provide a bandwidth up to 410MHz while drawing only 4.1mA of quiescent current. With a slew rate of 940V/µs and an output stage optimized for driving a standard 100Ω load, this circuit is highly suitable for applications where speed and power-saving are the main requirements. The TSH350 is a single operator available in the tiny SOT23-5 and SO-8 plastic packages, saving board space as well as providing excellent thermal and dynamic performance. Pin connections (top view) VCC - VCC + + - Non-Inv. In. Inv. In. SOT23-5 Output 1 VCC - VCC + + - Non-Inv. In. Inv. In. SOT23-5 Output Inv. In. Non-Inv. In. VCC - VCC + NC NC Output+ NC SO-8 Inv. In. Non-Inv. In. VCC - VCC + NC NC Output+ NC SO-8 SOT23-5 SO-8
1 Absolute maximum ratings
Table 1. Absolute maximum ratings (AMR)
- All voltage values are measur ed with respect to the ground pin.
- Differential voltage is the non-inverting input termi nal with respect to the inverting input terminal.
- The magnitude of input and output voltage must never exceed V CC +0.3V.
- Short-circuits can cause excessive heating. Destructive dissipation can result from short-circuits on all
- Human body model: A 100pF capacitor is charged to the specified voltage, then discharged through a
while the other pins are floating.
- Machine model: A 200pF capacitor is charged to the specified voltage, then discharged directly between
connected pin combinations while the other pins are floating.
- Charged device model: all pins and the package are charged together to the specified voltage and then
discharged directly to the ground through only one pin. This is done for all pins.
Table 2. Operating conditions
- Tested in full production at 5V (±2.5V) supply voltage.
2 Electrical characteristics
Table 3. Electrical characteristics for V CC = ±2.5V, Tamb = 25°C (unless otherwise specified)
370 MHz
Table 4. Closed-loop gain and feedback components
3 Evaluation boards
- SOT23_SINGLE_HF BOARD Board for the evaluation of a single high-speed op-amp in SOT23-5 package.
- SO8_SINGLE_HF Board for the evaluation of a single high-speed op-amp in SO-8 package.
- SO8_DUAL_HF Board for the evaluation of a dual high-speed op-amp in SO-8 package.
- SO8_S_MULTI Board for the evaluation of a single high-speed op-amp in SO-8 package in inverting and non-inverting configuration, dual and single supply.
- SO14_TRIPLE Board for the evaluation of a triple high-speed op-amp in SO-14 package with video application considerations. Board material:
- 2 layers
- FR4 (εr=4.6)
- epoxy 1.6mm
- copper thickness: 35µm
Figure 29. Evaluation kit for high-speed op-amps
4 Power supply considerations
also be placed as close as possible to the IC pins. Bypass capacitors must be incorporated for both the negative and the positive supply. Note: On the SO8_SINGLE_HF board, these capacitors are C6, C7, C8, C9. Figure 30. Circuit for power supply bypassing and VOL, the amplifier will provide an output swing from +0.9V to +4.1V on a 100Ω load. evaluation board (see Evaluation boards on page 11).
its value is calculated with a consideration of the cut off frequency of this low-pass filter. Figure 31. Circuit for +5V single supply (using evaluation board SO8_S_MULTI)
5 Noise measurements
- eN is the input voltage noise of the amplifier
- iNn is the negative input current noise of the amplifier
- iNp is the positive input current noise of the amplifier
Figure 32. Noise model where ΔF is the specified bandwidth. where k is the Boltzmann's constant, equal to 1,374.10-23J/°K. T is the temperature (°K).
The input noise of the instrumentation must be extracted from the measured noise value. The real output noise value of the driver is: Equation 3 The input noise is called equivalent input noise because it is not directly measured but is evaluated from the measurement of the output divided by the closed loop gain (eNo/g). After simplification of the fourth and the fifth term of Equation 2 we obtain: Equation 4 Measurement of the input voltage noise eN If we assume a short-circuit on the non-inverting input (R3=0), from Equation 4 we can derive: Equation 5 In order to easily extract the value of eN, the resistance R2 will be chosen to be as low as possible. In the other hand, the gain must be large enough: R3=0, gain: g=100 Measurement of the negative input current noise iNn To measure the negative input current noise iNn, we set R3=0 and use Equation 5. This time, the gain must be lower in order to decrease the thermal noise contribution: R3=0, gain: g=10 Measurement of the positive input current noise iNp To extract iNp from Equation 3, a resistance R3 is connected to the non-inverting input. The value of R3 must be chosen in order to keep its thermal noise contribution as low as possible against the iNp contribution: R3=100W, gain: g=10 eNo 2 eN2 g2 iNn 2 R22 iNp 2+×+× R32× g2× R2 4kTR1 4kTR2 1 R2 4kTR3×++×+= eNo Measured() 2 instrumentation() 2–= eNo 2 eN2 g2 iNn 2 R22 iNp 2+×+× R32× g2× g4 k T R 2 1 R2 4kTR3×+×+= eNo eN 2 g2 iNn 2 R22 g4 k T R 2×+×+×=
6 Intermodulation distortion product
the amplitude of the harmonics of the output signal Vout. signal contributes to harmonic distortion and to the intermodulation product. characterizing the driving capability of multi-tone input signals.
- second order intermodulation terms IM2 by the frequencies (ω1-ω2) and (ω1+ω2) with an amplitude of C2A2
- third order intermodulation terms IM3 by the frequencies (2ω1-ω2), (2ω1+ω2), (−ω1+2ω2) and (ω1+2ω2) with an amplitude of (3/4)C3A3 The intermodulation product of the driver is measured by using the driver as a mixer in a summing amplifier configuration (see Figure 33). In this way, the non-linearity problem of an external mixing device is avoided.
Figure 33. Inverting summing amplifier (using evaluation board SO8_S_MULTI)
7 Inverting amplifier biasing
Figure 34. Compensation of the input bias current
8 Active filtering
Figure 35. Low-pass active filtering, Sallen-Key
9 Package information
Figure 36. SOT23-5 package mechanical data
Figure 37. SO-8 package mechanical data
Table 5. Order codes 1-Oct-2004 1 First release corresponding to Preliminary Data version of datasheet. 10-Dec-2004 2 Release of mature product datasheet. replaced by thermal resistance junction to case.