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LTC5564IUDPBF

UltraFast™ 7ns Response Time 15GHz RF Power Detector with Comparator

Linear Technology 

LTC5564

APPLICATIONS INFORMATION

Operation

The LTC5564 is a fast RF detector with a high speed

amplifier and comparator. This product integrates these

functions to provide RF detection over frequencies ranging

from 600MHz to 15GHz. These functions include an RF

Schottky peak detector, internally compensated operational

amplifier, and a comparator as shown in Figure 1. The

LTC5564 has selectable amplifier gains, amplifier output

offset adjustment and comparator latch enable capabilities.

Amplifier

The high speed amplifier offers four gain settings and

is capable of driving a 1.7mA load with an output swing

range of approximately 295mV to VCC – 1.6V. See Table 1

for gain setting operation.

The VOUTADJ pin provides output DC offset adjustment

to satisfy various interface requirements. Setting VOUT

to 500mV also provides the maximum demodulation

bandwidth in each gain mode. See Electrical and Typical

Performance Characteristics curve. See Table 1 for the

typical VOUTADJ voltage for the desired VOUT DC output

offset in each gain setting.

RF Detector

The internal temperature compensated Schottky diode

peak detector converts the RF input signal to a low

frequency signal. The detector demonstrates excellent

efficiency and linearity over a wide range of input power

levels. The Schottky diode is nominally biased at 180µA

and drives a parallel reservoir capacitor-resistor network

of 8pF and 1.2k.

Comparator

The high speed comparator compares the external refer-

ence voltage on the VREF pin to the internal signal voltage

VP from the peak detector and produces the output logic

signal VCOMP . VP is the internal comparator positive input

as shown in Figure 1.

LEN provides latch enable/disable functionality as shown

in Figure 2.

Table 1. Gain Mode and Typical VOUTADJ Operation

PIN

G1

G0

GAIN MODE DESCRIPTION

GND GND

GAIN1

Minimum Gain Setting (VOUT/RFIN ≈ 1.5dB)

GND

VCCA

GAIN2

VOUT/RFIN Increased 6dB

VCCA

GND

GAIN4

VOUT/RFIN Increased 12dB

VCCA

VCCA

GAIN8

VOUT/RFIN Increased 18dB

Note: Valid range for VOUT ≈ 0.195V ≤ VOUT ≤ VCC – 1.6

REQUIRED VOUTADJ FOR A GIVEN DC OUTPUT OFFSET

VOUTADJ = 0.95 • VOUT – 0.174

VOUTADJ = (VOUT – 0.07)/2.10

VOUTADJ = (VOUT + 0.05)/3.16

VOUTADJ = (VOUT + 0.25)/5.26

LEN

VREF

VP

VCOMP

VOUT

TRANSPARENT

VOUT

LATCHED

5564 F02

VOUT

TRANSPARENT

Figure 2. LTC5564 Comparator Latch Enable Function

5564fc

10

For more information www.linear.com/LTC5564

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