KH300

www.fairchildsemi.com KH300 Wideband, High-Speed Operational Amplifier Features I I I I I General Description The KH300 operational amplifier is a current feedback amplifier that provides a DC-85MHz -3dB bandwidth that is virtually independent of gain setting. Rise and fall times of 4ns and drive capability of 22Vpp and 100mA add to the KH300’s impressive specifications. Using the KH300 is as easy as adding power supplies and a gain-setting resistor. Unlike conventional op amp designs in which optimum gain-bandwidth product occurs at a high gain, minimum settling time at a gain of -1, maximum slew rate at a gain of +1, et cetera, the KH300 offers consistent performance at gain settings from 1 to 40 inverting or non-inverting. As a result, designing with the KH300 is greatly simplified. And since no external compensation is necessary, “tweeks” on the production line have been eliminated, making the KH300 an efficient component for use in production situations. Flat gain and phase response from DC to 45MHz and superior rise and fall times make the KH300 an ideal amplifier for a broad range of pulse, analog, and digital applications. A 45MHz full power bandwidth (20Vpp into 100Ω) and 3000V/µsec slew rate eliminate the need for power buffers in many applications such as driving “flash” A to D converters or linedriving. For applications requiring lower power consumption, the KH300 can operate on supplies as low as ±5V. Fast overload recovery (20ns) helps prevent loss of data in communications applications and flat phase response reduces distortion, even when data must be sent over extended lengths of line. The KH300A is packaged in a side-brazed 24-pin ceramic DIP and is specified at 25°C. -3dB bandwidth of 85MHz 3000V/µsec slew rate 4ns rise and fall time 100mA output current Low distortion, linear phase Applications I I I I I I Digital communications Baseband and video communications Instrument input/output amplifiers Fast A to D, D to A conversion Graphic CRT video drive amp Coaxial cable line driver 16 +VCC V+ 6 + 12 Vo V- 8 1500 11 Rf 13 24 -VCC GND KH300 Equivalent Circuit Diagram Pin 11 provides access to a 1500Ω feedback resistor which can be connected to the output or left open if an external feedback resistor is desired. All undesignated pins are internally unconnected. REV. 1A February 2001 DATA SHEET KH300 KH300 Electrical Characteristics magnitude of gain {|Vout/Vin|] PARAMETERS Frequency Domain Response -3dB bandwidth gain flatness phase shift deviation from linear phase reverse isolation distortion Time Domain Response rise and fall time CONDITIONS (25°C, VCC = ±15V, RL = 100Ω; unless noted) 4* TYP 105 45 ±0.25 ±0.5 1 2 60 MIN2 75 20 TYP 85 45 ±0.08 ±0.25 1.6 3 70 MAX2 40 TYP 70 45 ±0.25 ±1 2 5 70 UNITS MHz MHz dB dB deg/MHz deg dB Vo < 4Vpp Vo = 20Vpp 100KHz to 20MHz 20MHz to 45MHz DC to 45MHz refer to graphs ±0.3 ±0.6 5V output step 20V output step settling time to 0.8% 10V output step overshoot (input rise time ≤ 1ns) 5V output step slew rate overload recovery (200% od) < 50ns pulse width General Information input offset voltage (drift) input bias current (drift) CONDITIONS 3 7 20 5 3 20 MIN2 4 7 20 5 3 20 TYP 10(25) 10(20) 30(50) 22 48 100K/3 60 64 10, 100 24 MAX2 32 30 100 56 38 5 7 25 5 3 20 ns ns ns % V/µs ns UNITS mV(µV/°C) µV(nA/°C) µV(nA/°C) µV -dBc Ω/pF dB dB V, mA mA non-inverting inverting equivalent input noise1 integrated 0.1 to 100MHz, (Rs = 50Ω, gain = 20) second/third harmonic distortion 20MHz, +10dBm input impedance non-inverting power supply rejection ratio input referred common mode rejection ratio input referred output drive voltage,current supply current 45 33 Min/max ratings are based on product characterization and simulation. Individual parameters are tested as noted. Outgoing quality levels are determined from tested parameters. NOTES: 1) For Noise Figure, refer to Distortion and Noise section in text. 2) 100% tested at +25°C, AV = +20, RL = 100Ω, and VCC = ±15V. * Refer to Low Gain Operation section. Absolute Maximum Ratings supply voltage (±VCC) output current (Io) input voltage (Vimax) common mode input voltage power dissipation junction temperature (TJ) storage temperature still air thermal resistance (θca) 16V (±5V min) 100mA (|VCC| - 2.5)/AV ±1/2 |VCC| refer to graph 150°C -55°C to +150°C +25°C/W 2 REV. 1A February 2001 KH300 DATA SHEET KH300 Performance Characteristics (25°C, VCC = ±15V, RL = 100Ω; unless noted) Non-Inverting Gain Inverting Gain Relative Gain (1dB/div) Av = 4 Relative Gain (1dB/div) Av = 4 Av = 20 Av = 20 Av = 40 Av = 40 0 10 20 30 40 50 60 70 80 90 100 0 10 20 30 40 50 60 70 80 90 100 Freguency (MHz) Broadband Inverting & Non-Inverting Gain Av = 20 Freguency (MHz) Inverting & Non-Inverting Phase Av = 20 Relative Gain (10dB/div) 0° Inverting Non-inverting -180° -90° Non-inverting Inverting -270° -180° -360° 0 100 200 300 400 500 600 700 800 900 1GHz 0 10 20 30 40 50 60 70 80 90 100 Freguency (MHz) 2nd & 3rd Harmonic Distortion Intercept 90 Av = 20 Freguency (MHz) 2-Tone 3rd Order Intermod. Intercept 50 Av = 20 Intercept Point (+dBm) Intercept Point (+dBm) 107 108 80 70 60 50 40 30 104 (I2) 2nd harmonic intercept exceeds 90dBm below 105Hz 45 40 35 30 (I3) 3rd harmonic intercept exceeds 64dBm below 105Hz 25 105 106 0 20 40 60 80 100 Freguency (Hz) Non-Inverting Small Signal Pulse Resp. Av = 20 Freguency (MHz) Inverting Small Signal Pulse Response Av = -20 Output Voltage (1V/div) Time (5ns/div) Output Voltage (1V/div) Time (5ns/div) REV. 1A February 2001 3 DATA SHEET KH300 KH300 Performance Characteristics (25°C, VCC = ±15V, RL = 100Ω; unless noted) Large Signal Pulse Response 0.4 Av = -20 Settling Time 10V step Av = 20 Output Voltage (2V/div) 0.2 Settling Error (%) Time (5ns/div) 0 -0.2 -0.4 -0.6 -0.8 0 200 400 600 800 1000 Time (ns) Relative Bandwidth vs. VCC 1.1 Av = 20 Power Dissipation Derating 2.5 1.0 Circuit Power Dissipation (W) 150°C max TJ VCC = ±15V Relative Bandwidth 2.0 Case Ambient 0.9 1.5 0.8 1.0 0.7 4 6 8 10 12 14 16 0.5 -25 0 25 50 75 100 VCC (V) Equivalent Input Noise 100 100 80 70 Temperature (°C) Common Mode Rejection Ratio Voltage Noise (nV/√Hz) Current Noise (pA/√Hz) Inverting Current 11pA/√Hz CMRR (dB) 60 50 40 30 101 102 103 104 105 106 107 10 Voltage 2.9nV/√Hz Non-inverting Current 2.3pA/√Hz 10 1 102 103 104 105 106 107 108 1 Frequency (Hz) Power Supply Rejection Ratio 80 70 Frequency (Hz) CMRR (dB) 60 50 40 30 101 102 103 104 105 106 Frequency (Hz) 4 REV. 1A February 2001 KH300 DATA SHEET Layout Considerations To assure optimum performance the user should follow good layout practices which minimize the unwanted coupling of signals between nodes. During initial breadboarding of the circuit, use direct point to point wiring, keeping lead lengths to less than 0.25”. The use of solid, unbroken ground plane is helpful. Avoid wire-wrap type pc boards and methods. Sockets with small, short pin receptacles may be used with minimal performance degradation although their use is not recommended. +15 and 16. Larger tantalum capacitors should also be placed within one inch of these pins. To prevent signal distortion caused by reflections from impedance mismatches, use terminated microstrip or coaxial cable when the signal must traverse more than a few inches. Since the pc board forms such an important part of the circuit, much time can be saved if prototype boards of any high frequency sections are built and tested early in the design phase. Controlling Bandwidth and Passband Response As with any op amp, the ratio of the two feedback resistors Rf and Rg, determines the gain of the KH300. Unlike conventional op amps, however, the closed loop polezero response of the KH300 is affected very little by the value of Rg. Rg scales the magnitude of the gain, but does not change the value of the feedback. Rf does influence the feedback and so the KH300 has been internally compensated for optimum performance with Rf = 1500Ω, but any value of Rf > 500Ω may be used with a single capacitor placed between pins 8 and 12 for compensation. See table 1. As Rf decreases, Cc must increase to maintain flat gain. Large values of Rf and Cc can be used together or separately to reduce the bandwidth. This may be desirable for reducing the noise bandwidth in applications not requiring the full frequency response available. Table 1: Bandwidth vs. Rf and Cc (Av = +20) 0.01µF Vin Ri 50Ω Rg 22µF 16 6 8 + 11 KH300 24 13 12 Ro 50Ω 1/2 Vo RL 50Ω -15 22µF 0.01µF Av = 1 + Rf Rg Rf = 1500Ω (internal) Figure 1: Recommended Non-inverting Gain Circuit +15 Rf (KΩ) 0.01µF 51 22µF 6 16 Cc (pF) 0 0 0 0 0.3 1.1 1.9 f±0.3dB (MHz) 2 3 8 45 90 95 110 f-3.0dB (MHz) 5 12 40 85 115 130 135 Vin Ri 50Ω Rg 8 + 11 KH300 24 13 12 Ro 50Ω 1/2 Vo RL 50Ω 10.0 5.0 2.0 1.5 1.0 0.75 0.50 -15 22µF 0.01µF For Zin = 50Ω Select: Rg||Ri = 50 Rf -Av = Rg Rf = 1500Ω (internal) Figure 2: Recommended Inverting Gain Circuit During pc board layout keep all traces short and direct. Rf and Rg should be as close as possible to pin 8 to minimize capacitance at that point. For the same reason, remove ground plane from the vicinity of pins 8 and 6. In other areas, use as much ground plane as possible on one side of the pc board. It is especially important to provide a ground return path for current from the load resistor to the power supply bypass capacitors. Ceramic capacitors of 0.01 to 0.1µF should be close to pins 13 Low Gain Operation The small amount of stray capacitance present at the inverting input can cause peaking which increases with decreasing gain. The gain setting resistor Rg is effectively in parallel with this capacitance and so a frequency domain pole results. With small Rg (Gain > 8), this pole is at a high frequency and it affects the closed loop gain of the KH300 only slightly. At lower values of gain, this pole becomes significant. For example, at a gain of +2, the gain may peak as much as 3dB at 75MHz, and have a bandwidth exceeding 150MHz. The same behavior does not exist for low inverting gains, however, since the inverting input is a virtual ground which maintains a constant voltage across the stray capacitance. Even at inverting gains