U2894B Datasheet, PDF (7/16 Pages) TEMIC Semiconductors – Modulation PLL for GSM, DCS and PCS Systems

U2894B
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
1
2
3
4
5
Mode Selection
Resistance between
Pin MC and Pin VS2
0 (<50 W)
W 2.7 k (±5%)
10 kW (±5%)
R^{36 kW (±5%)}
(>1 MW)
N-Divider
1:1
1:1
1:1
2:1
2:1
R-Divider
1:1
1:1
2:1
2:1
2:1
CPO Current Polarity ⁴⁾
f_N < f_R ¹⁾ f_N > f_R ¹⁾
Sink
Source
Source
Source
Sink
Source
Sink
Sink
Sink
Source
Application
PCN/PCS ²⁾
GSM ³⁾
1) _{Frequencies referred to PFD input}
2) _{LO frequencies below VCO frequency}
3) _{LO frequencies above VCO frequency}
4_{) Sink current into Pin CPO. Source: current out from Pin CPO.}
Equivalent Circuits at the IC’s Pins
V_{Bias_MDLO}
L,Q
NI, NQ
MDLO
2230 Ω
2230 Ω
250 Ω
VS1
MDO
NMDO
V_{Ref_input}
Baseband input
V_{Ref_MDLO}
30 pF
LO input
Figure 5. I/Q modulator
V_{Ref_output}
Output
GND
14553
RF
NRF
1 kΩ
V_{Bias_RF}
1 kΩ
V_{Bias_LO}
890 Ω
890 Ω
MIXLO
1.6 kΩ
V_{Ref_RF}
V_{Ref_LO}
1.6 kΩ
40 pF
LO input
Output
Figure 6. Mixer
VS3
6.3 Ω
MIXO
GND
14554
Rev. A4, 30-Sep-98
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