LT5524 Low Distortion IF Amplifier/ADC Driver with Digitally Controlled Gain UFEATURESDESCRIPTIO ■ Output IP3 at 100MHz: 40dBm The LT®5524 is a programmable gain amplifier (PGA) with ■ Maximum Output Power: 16dBm bandwidth extending from low frequency (LF) to 540MHz. ■ Bandwidth: LF to 540MHz It consists of a digitally controlled variable attenuator, ■ Propagation Delay: 0.8ns followed by a high linearity amplifier. Four parallel digital ■ Maximum Gain: 27dB inputs control the gain over a 22.5dB range with 1.5dB ■ Gain Control Range: 22.5dB step resolution. An on-chip power supply regulator/filter ■ Gain Control Step: 1.5dB helps isolate the amplifier signal path from external noise ■ Gain Control Settling Time: 500ns sources. ■ Noise Figure: 8.6dB at 100MHz (Max Gain) The LT5524’s open-loop architecture offers stable opera- ■ Output Noise Floor: –138dBm/Hz (Max Gain) tion for any practical load conditions, including peaking- ■ Reverse Isolation: –92dB free AC response when driving capacitive loads, and ■ Single Supply: 4.75V to 5.25V excellent reverse isolation. ■ Shutdown Mode ■ Enable/Disable Time: 1µs The LT5524 may be operated broadband, where the out- ■ Differential I/O Interface put differential RC time constant sets the bandwidth, or it ■ 20-Lead TSSOP Package may be used as a narrowband driver with the appropriate U output filter. , LTC and LT are registered trademarks of Linear Technology Corporation. APPLICATIO S Patents Pending. ■ High Linearity ADC Driver ■ IF Sampling Receivers ■ VGA IF Power Amplifier ■ 50Ω Driver ■ Instrumentation Applications UTYPICAL APPLICATIOOutput IP3 vs Frequency, ROUT = 200 Ω 54 5V 51 CHOKE CHOKE 48 0.1µF 0.1µF 45 MAX GAIN RF IF IF LT5524 100Ω ADC INPUT BPF AMP 42 OIP3 (dBm) 5524 TA01 LO 39 0.1µF 0.1µF 1.5dB GAIN CONTROL 36 ATTENUATION 4 LINES STEP 33 30 0 50 100 150 200 FREQUENCY (MHz) 5524 TA02 5524f 1