Quadrature Modulator
CMX993/CMX993W
C1 33nF
C2 Note 1
C3 Note 1
C4 33nF
C5 1F
R1 10k
R2 5.1k
R3 10k
R4 5.1k
R5 5.1k
R6 10
R7 10
R8 10
R9 10
R10 5.1k
R11 5.1k
R12 10 k
R13 5.1k
R14 10k
Resistors 5%, capacitors and inductors 20% unless otherwise stated
Note1: Value should be selected depending on modulation bandwidth:
33nF typically for CMX993, 3.3nF typically for CMX993W
Table 4 Quadrature Modulator and Input Circuits: Typical Components
4.3
Local Oscillator Input
A 1:1 balun transformer should be used on the local oscillator input for optimum performance. In the local-
oscillator divide by 4 mode, a single ended input may be used by decoupling the LON pin to ground and
applying the LO signal to LOP noting that a dc path to ground on LOP must still be provided.
The divide by 4 mode is not recommended for operation below 200MHz LO frequency (50MHz RF output).
For output frequencies below 50MHz the divide by 2 mode is recommended.
Users should be aware that the presence of high levels of harmonics in the signal applied to the LO Input
might degrade quadrature accuracy.
T1
LOP
C1
LON
LO INPUT
(Optional)
CMX993/CMX993W
Figure 5 LO Input Configuration using a 1:1 Balun (60MHz to 2GHz)
C1 1nF
T1 Balun 1:1 (e.g. MABA-007748-CT11160)
from M/A-com, see Note 3)
Notes:
1. The configuration of the 1:1 balun used at the LO input has to create a dc path to analogue GND
for both LO inputs, LOP and LON as shown in Figure 5.
2. The capacitor C1 is optional and should be used where the 0V dc connection provided by the
balun is not acceptable to the circuitry providing the LO signal.
3. The MABA-007748-CT11160 is specified between 5MHz and 1.2GHz. The part has been found to
remain functional with the CMX993/CX993W up to at least 2GHz however such operation is
outside the manufacturer's rating.
2013 CML Microsystems Plc
10
D/993/10
CMLMICRO [ CML MICROCIRCUITS ]
