For price, delivery and to place orders: Hittite Microwave Corporation, 2 Elizabeth Drive, Chelmsford, MA 01824

Phone: 978-250-3343

Fax: 978-250-3373

Order On-line at www.hittite.com

Application Support: Phone: 978-250-3343 or apps@hittite.com

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HMC1197LP7FE

v00.0912

WIDEBAND DIRECT QUADRATURE MODULATOR

w/ FRACTIONAL-N PLL & VCO, 100 - 4000 MHz

I/Q modulator includes a LO quadrature phase splitter that generates two carrier signals in quadrature followed by

LO limiting amplifiers which are used to drive the I and Q mixers with saturated signal levels. Therefore, the LO path

is immune to large variations in the LO input signal level and the modulator performance does not vary much with LO

input power.

After upconversion, the outputs of the I and Q mixers are summed together differentially and converted to single-

ended RF output. The single-ended RF output port is internally matched to 50 Ohms and does not require any

external matching components. Only a standard DC-blocking capacitor is required at this interface.

Harmonic Low Pass Filter

High LO harmonic content causes amplitude and phase mismatches and ultimately performance degradation in

modulator sideband rejection.

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hmc701 Sweeper Plot 11:18:12 AM 3/19/2012

LO HARMONIC LEVEL (dBc)

3rd LO Harmonic

2nd LO Harmonic

Targeted minimum LO harmonic level

Targeted maximum modulator

sideband rejection

Figure 2. Typical impact of 2nd and 3rd LO harmonic on sideband rejection.

As shown in Figure 2, in a typical modulator with 1xLO input both the 2nd and 3rd LO harmonics affect the modulator

the LO signal level.

Figure 3 shows the typical insertion loss of the low pass filter.

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9000

FREQUENCY (MHz)

Band 0

Band 7

Band 8

Band 15

Low Bands

High Bands

Figure 3. Insertion loss of the low pass filter.