Single Supply

The MAX4526/MAX4527 operate from a single supply

between +4.5V and +36V when V- is connected to

GND. Observe all of the bipolar precautions when

operating from a single supply.

__________Applications Information

The MAX4526/MAX4527 are designed for DC and

low-frequency-signal phase-reversal applications. Both

DC and AC symmetry are optimized for use with ±15V

supplies.

Signal Phase/Polarity Reversal

The MAX4526/MAX4527 can reverse the phase or

polarity of a pair of signals that are out-of-phase and

balanced to ground. This is done by routing signals

through the MAX4526/MAX4527 and under control of

the IN pin, reversing the two signals paths inside the

switch before sending out to a balanced output. Figure

1 shows a typical example. The MAX4526/MAX4527

cannot reverse the phase or polarity of a single-

grounded signal, as can be done with an inverting

op amp or transformer.

Balanced Modulators/Demodulators

The MAX4526/MAX4527 can be used as a balanced

modulator/demodulator at carrier frequencies up to

100kHz (Figure 2). Higher frequencies are possible, but

as frequency increases, small imbalances in the

MAX4526/MAX4527’s internal capacitance and resis-

tance gradually impair performance. Similarly, imbal-

ances in external circuit capacitance and resistance to

GND reduce overall carrier suppression.

The carrier is applied as a logic-level square wave to

IN. (Note that this voltage can go as negative as V-.)

For best carrier suppression, the power-supply volt-

ages should be equal, the square wave should have a

precise 50% duty cycle, and both the input and output

signals should be symmetrical about ground. Bypass

V+ and V- to GND with 0.1µF ceramic capacitors, as

close to the IC pins as possible. Since the logic-level

translator/driver in the MAX4526 is faster than the one

in the MAX4527, it gives better results at higher

frequencies. In critical applications, carrier suppression

can be optimized by trimming duty cycle, DC bias

around GND, or external source and load capacitance.

In signal lines, balancing both capacitance and resis-

tance to GND produces the best carrier suppression.

Transformer coupling of input and output signals

provides the best isolation and carrier suppression.

Transformers can also provide signal filtering, imped-

ance matching, or low-noise voltage gain. Use a

center-tapped transformer or high-resistance voltage

divider to provide a DC path to GND on either the input

signal or output signal. This ensures a DC path to GND

and symmetrical operation of the internal switches.

Phase-Reversal Analog Switches

8

_______________________________________________________________________________________

50%

0V

0V

V-

X

B

A

-10V

+10V

V-

300

Ω

GND

V- IS CONNECTED TO GND (0V) FOR SINGLE-SUPPLY OPERATION.

IN

V+

50

Ω

90%

90%

35pF

V+

V+

MAX4526

MAX4527

______________________________________________Test Circuits/Timing Diagrams

Figure 3. Address Transition Time