U2895B

Rev. A3, 30-Sep-98

7 (16)

Mode Selection

The device can be programmed to different modes via an external resistor RMODE (including short, open) from Pin MC

to VS2. The mode is distinguished from specific N-, R-divider ratios, and the polarity of the charge pump current.

Mode Selection

N-Divider

R-Divider

Application

Mode

Resistance between

Pin MC and Pin VS2

1

0 (<50

W)

1:1

1:1

Sink

Source

2

2.7 k

W (±5%)

1:1

1:1

Source

Sink

3

10 k

W (±5%)

1:1

2:1

Source

Sink

4

47 k

W (±5%)

2:1

2:1

Source

Sink

5

R (>1 MW)

2:1

2:1

Sink

Source

1)

Frequencies referred to PFD input

2)

LO frequencies below VCO frequency

3)

LO frequencies above VCO frequency

Sink current into Pin CPO. Source: current out from Pin CPO.

Equivalent Circuits at the IC’s Pins

L,Q

NI, NQ

250

Ω

30 pF

2230

Ω

2230

Ω

VS1

MDO

NMDO

GND

Baseband input

LO input

Output

15049

MDLO

V

Bias_MDLO

V

Ref_input

V

Ref_MDLO

V

Ref_output

Figure 5. I/Q modulator

14554

NRF

LO input

890

Ω

890

Ω

1 k

Ω

Output

1.6 k

Ω

1.6 k

Ω

1 k

Ω

RF

MIXLO

40 pF

6.3

Ω

MIXO

VS3

GND

V

Bias_RF

V

Ref_RF

V

Bias_LO

V

Ref_LO

Figure 6. Mixer