Radiation Hardened, Ultra High Speed Current Feedback Amplifier
The is a radiation hardened high speed, wideband, fast settling current feedback amplifier. Built with Intersil's proprietary, complementary bipolar UHF-1 (DI bonded wafer) process, it is the fastest monolithic amplifier available from any semiconductor manufacturer. These devices are QML approved and are processed and screened in full compliance with MIL-PRF-38535. The HS-1100RH's wide bandwidth, fast settling characteristic, and low output impedance make this amplifier ideal for driving fast A/D converters. Component and composite video systems will also benefit from this amplifier's performance, as indicated by the excellent gain flatness, and 0.03%/0.05 Deg. Differential Gain/Phase specifications (RL = 75). Specifications for Rad Hard QML devices are controlled by the Defense Supply Center in Columbus (DSCC). The SMD numbers listed here must be used when ordering. Detailed Electrical Specifications for these devices are contained in SMD 5962-94676. A "hot-link" is provided on our homepage for downloading. http://www.intersil.com/spacedefense/space.htm
· Electrically Screened to SMD # 5962-94676· QML Qualified per MIL-PRF-38535 Requirements· Low Distortion 30MHz). -84dBc (Typ)· Wide -3dB Bandwidth. 850MHz (Typ)· Very High Slew Rate. 2300V/µs (Typ)· Fast Settling (0.1%). 11ns (Typ)· Excellent Gain Flatness (to 50MHz). 0.05dB (Typ)· High Output Current. 65mA (Typ)· Fast Overdrive Recovery. <10ns (Typ)· Total Gamma Dose. 300kRAD(Si)· Latch Up. None (DI Technology)
· Video Switching and Routing· Pulse and Video Amplifiers· Wideband Amplifiers· RF/IF Signal Processing· Flash A/D Driver· Imaging Systems
ORDERING NUMBER 5962F9467602VPC HFA1100IJ (Sample) HFA11XXEVAL INTERNAL MKT. NUMBER HS7B-1100RH-Q HFA1100IJ Evaluation Board TEMP. RANGE (oC) to 85
CAUTION: These devices are sensitive to electrostatic discharge; follow proper IC Handling Procedures. 321-724-7143 | Copyright © Intersil Corporation 1999
The enclosed plots of inverting and non-inverting frequency response illustrate the performance of the HS-1100RH in various gains. Although the bandwidth dependency on closed loop gain isn't as severe as that of a voltage feedback amplifier, there can be an appreciable decrease in bandwidth at higher gains. This decrease may be minimized by taking advantage of the current feedback amplifier's unique relationship between bandwidth and RF. All current feedback amplifiers require a feedback resistor, even for unity gain applications, and , in conjunction with the internal compensation capacitor, sets the dominant pole of the frequency response. Thus, the amplifier's bandwidth is inversely proportional to RF. The HS-1100RH design is optimized for at a gain of +1. Decreasing in a unity gain application decreases stability, resulting in excessive peaking and overshoot. At higher gains the amplifier is more stable, so RF can be decreased in a trade-off of stability for bandwidth. The table below lists recommended RF values for various gains, and the expected bandwidth.
traces connected to -IN, and connections to -IN should be kept as short as possible. An example of a good high frequency layout is the Evaluation Board shown in Figure 2.
Capacitive loads, such as an A/D input, or an improperly terminated transmission line will degrade the amplifier's phase margin resulting in frequency response peaking and possible oscillations. In most cases, the oscillation can be avoided by placing a resistor (RS) in series with the output prior to the capacitance. Figure 1 details starting points for the selection of this resistor. The points on the curve indicate the RS and CL combinations for the optimum bandwidth, stability, and settling time, but experimental fine tuning is recommended. Picking a point above or to the right of the curve yields an overdamped response, while points below or left of the curve indicate areas of underdamped performance.
The frequency response of this amplifier depends greatly on the amount of care taken in designing the PC board. The use of low inductance components such as chip resistors and chip capacitors is strongly recommended, while a solid ground plane is a must! Attention should be given to decoupling the power supplies. A large value (10µF) tantalum in parallel with a small value (0.1µF) chip capacitor works well in most cases. Terminated microstrip signal lines are recommended at the input and output of the device. Capacitance directly on the output must be minimized, or isolated as discussed in the next section. Care must also be taken to minimize the capacitance to ground seen by the amplifier's inverting input (-IN). The larger this capacitance, the worse the gain peaking, resulting in pulse overshoot and possible instability. To this end, it is recommended that the ground plane be removed under
FIGURE 1. RECOMMENDED SERIES OUTPUT RESISTOR vs LOAD CAPACITANCE
RS and CL form a low pass network at the output, thus limiting system bandwidth well below the amplifier bandwidth 850MHz. By decreasing as CL increases (as illustrated in the curves), the maximum bandwidth is obtained without sacrificing stability. Even so, bandwidth does decrease as you move to the right along the curve. For example, = 30pF, the overall bandwidth is limited to 300MHz, and bandwidth drops = 340pF.
The performance of the HS-1100RH may be evaluated using the HFA11XXEVAL Evaluation Board. The layout and schematic of the board are shown in Figure 2. To order evaluation boards, please contact your local sales office.
FIGURE 2C. SCHEMATIC FIGURE 2. EVALUATION BOARD SCHEMATIC AND LAYOUT
Device Characterized at: VSUPPLY = 100, Unless Otherwise Specified PARAMETERS Input Offset Voltage (Note 1) Average Offset Voltage Drift VIO CMRR VIO PSRR +Input Current (Note 1) Average +Input Current Drift - Input Current (Note 1) Average -Input Current Drift +Input Resistance - Input Resistance Input Capacitance Input Noise Voltage (Note 1) +Input Noise Current (Note 1) -Input Noise Current (Note 1) Input Common Mode Range Open Loop Transimpedance = 100kHz VCM = 0V Versus Temperature VCM = ±1.25V VCM = 0V Versus Temperature VCM = 0V Versus Temperature VCM = ±2V CONDITIONS TEMPERATURE 25oC Full 25oC Full 25oC Full 25oC Full 25oC TYPICAL UNITS mV µV/oC dB µA nA/oC µA nA/oC k pF nV/Hz pA/Hz V k