 |
Electronic Components Datasheet Search |
|
|
Electronic Components Datasheet Search |
|
ML2721 Datasheet(PDF) 11 Page - Micro Linear Corporation |
|
||||||||||||||||||||||||||||||
ML2721 Datasheet(HTML) 11 Page - Micro Linear Corporation |
|
|
11 / 27 page  ML2721 11 January, 2000 PRELIMINARY DATASHEET PRELIMINARY The signal flow in RECEIVE mode is from the RF input, through an image reject mixer, IF filter, hard limiter, Frequency to Voltage converter, data filter and data slicer. The ML2721 uses a single conversion super heterodyne receiver with a nominal IF of 1.024 MHz. An AGC subsystem extends the dynamic range of the receiver. The IF frequency and filter bandwidths are given in Table 3. Major features of the receiver are: n High dynamic range mixers with 10dB noise figure, – 15dBm IP3, 35dB image rejection (typical) n 6-pole bandpass IF filter, with accurate Gaussian to 12dB response n Center frequency 1.024MHz, Bandwidth 1.408 MHz (nominal) n Limiting IF amplifiers with >80dB gain, and excellent AM rejection n AGC to extend the dynamic range of the integrated filters & RSSI n Logarithmic RSSI output from Limiter; AGC state is information added to give 80dB range n FM demodulation by a linear F-to-V converter n 5-pole low-pass data filter with an accurate Gaussian response and 3dB cutoff at 768kHz (nominal) n 2 level data slicer with DC offset removal The output of the receiver is quantized in amplitude (to 1 bit) but there is no internal timing recovery. Timing recovery is performed in the external baseband circuits. ILO QLO DATA FILTER FCOMP ∫ F V FREF or FREF/2 I Q CAL TONE GEN TRACKING COUNTER MODES OF OPERATION (CONTINUED) Table 3. Filter Parameters to Division Ratio o i t a R n o i s i v i D e c n e r e f e R6 2 1 r e t e m a r a P0 = 0 D R1 = 0 D R y c n e u q e r f r e t n e c r e t l i f F I6 / F E R2 1 / F E R h t d i w d n a b r e t l i f F I4 . 4 / F E R8 . 8 / F E R r e t l i f a t a d e v i e c e R8 / F E R6 1 / F E R y c n e u q e r f r e t n e c r e t r e v n o c V o t F6 / F E R2 1 / F E R FILTER ALIGNMENT In RXCAL mode the receiver is not functional. Instead, the ML2721 filter alignment function tunes all the internal filters using the reference frequency from the REF pin. See Figure 2. The IF filter, data filters, and the F-to-V converter all have their frequency responses governed by RC time constants. Every capacitor that affects the frequency response includes a binary weighted capacitor array controlled by a 7 bit tuning bus. In RXCAL mode a reference tone at the IF center frequency is routed to the F-to-V converter. A digital tracking loop then adjusts the tuning word until there is mid-rail output from the F-to-V converter. This tracking loop may take up to 300µs to tune the filter when XCEN is asserted, but the tracking loop will continue to make small adjustments whenever the ML2721 is in RXCAL mode. Because all the filters in the chip are tuned in this manner, centering the F-to-V converter sets up the correct center frequencies and bandwidths for all the filters. The ML2721 must be placed in RXCAL mode for 300µs whenever XCEN is asserted to give time for the filters to align completely. Data Slicer The data slicer is a comparator that is AC coupled to the receive data filter output. The output is logic high or logic low. This circuit is designed to rapidly acquire valid data at the beginning of a received packet of data. The nominal time constant for the AC coupling is 9µs. This limits the maximum recommended run length to four ones or zeroes at 1.3Mbps. Longer run lengths require the use of a more complex external data slicer circuit. Data Output Drive The ML2721 DOUT pin is designed to drive a PCB trace and a single logic input with controlled slew rates. Buffer the output when driving any logic load greater than 5pF ( i.e., more than an ´10 oscilloscope probe or a single CMOS logic input pin). Figure 2. Dual Modulus Signal Divider |
Similar Part No. - ML2721 |
|
Similar Description - ML2721 |
|
|
Link URL |
| Privacy Policy |
| ALLDATASHEET.COM |
| Does ALLDATASHEET help your business so far? [ DONATE ] |
About Alldatasheet | Advertisement | Datasheet Upload | Contact us | Privacy Policy | Link Exchange | Manufacturer List All Rights Reserved©Alldatasheet.com |
| Russian : Alldatasheetru.com | Korean : Alldatasheet.co.kr | Spanish : Alldatasheet.es | French : Alldatasheet.fr | Italian : Alldatasheetit.com Portuguese : Alldatasheetpt.com | Polish : Alldatasheet.pl | Vietnamese : Alldatasheet.vn Indian : Alldatasheet.in | Mexican : Alldatasheet.com.mx | British : Alldatasheet.co.uk | New Zealand : Alldatasheet.co.nz |
|
Family Site : ic2ic.com |
icmetro.com |
English ▼
English
Chinese
German
Japanese
Russian
Korean
Spanish
French
Italian
Portuguese
Polish
Vietnamese
Indian
Mexican
British
New Zealand
