+

+

+

–

I

Q

DAC

DAC

A

B

LO

Quadrature

Modulator

DAC5686

cos(w

ct)

sin(w

ct)

sin(w

ct)

cos(w

ct)

A(t) = I(t)cos(w

w

c

c

t) – Q(t)sin(

t)

B(t) = I(t)sin(w

w

c

c

t) + Q(t)cos(

t)

cos(w

LOt)

sin(w

LOt)

0°

90°

IF(t) = I(t)cos(w

w

w

w

c

LO

c

LO

+

)t

– Q(t)sin(

+

)t

B0022–01

0

0

ω

c

ω

ω

ω

ω

LO

ω

LO – ωc

ω

LO + ωc

Real Input

Spectrum

to DAC5686

Complex Input

Spectrum

to Quadrature Modulator

Output Spectrum

to Quadrature Modulator

M0016-01

DAC5686

www.ti.com ............................................................................................................................................................ SLWS147F – APRIL 2003 – REVISED JUNE 2009

Figure 20. DAC5686 in SSB Mode With Quadrature Modulator

Figure 21. Spectrum After First and Second Up-Converson for Real Input

Copyright © 2003–2009, Texas Instruments Incorporated

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