aboutsummaryrefslogtreecommitdiffstats
path: root/fpga/usrp2/sdr_lib/rx_dcoffset.v
diff options
context:
space:
mode:
Diffstat (limited to 'fpga/usrp2/sdr_lib/rx_dcoffset.v')
-rw-r--r--fpga/usrp2/sdr_lib/rx_dcoffset.v57
1 files changed, 57 insertions, 0 deletions
diff --git a/fpga/usrp2/sdr_lib/rx_dcoffset.v b/fpga/usrp2/sdr_lib/rx_dcoffset.v
new file mode 100644
index 000000000..9840e9e1f
--- /dev/null
+++ b/fpga/usrp2/sdr_lib/rx_dcoffset.v
@@ -0,0 +1,57 @@
+//
+// Copyright 2011 Ettus Research LLC
+//
+// This program is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with this program. If not, see <http://www.gnu.org/licenses/>.
+//
+
+
+
+module rx_dcoffset
+ #(parameter WIDTH=16,
+ parameter ADDR=8'd0,
+ parameter alpha_shift=20)
+ (input clk, input rst,
+ input set_stb, input [7:0] set_addr, input [31:0] set_data,
+ input [WIDTH-1:0] in, output [WIDTH-1:0] out);
+
+ wire set_now = set_stb & (ADDR == set_addr);
+
+ reg fixed; // uses fixed offset
+ wire [WIDTH-1:0] fixed_dco;
+
+ localparam int_width = WIDTH + alpha_shift;
+ reg [int_width-1:0] integrator;
+ wire [WIDTH-1:0] quantized;
+
+ always @(posedge clk)
+ if(rst)
+ begin
+ fixed <= 0;
+ integrator <= {int_width{1'b0}};
+ end
+ else if(set_now)
+ begin
+ //integrator <= {set_data[30:0],{(31-int_width){1'b0}}};
+ fixed <= set_data[31];
+ end
+ else if(~fixed)
+ integrator <= integrator + {{(alpha_shift){out[WIDTH-1]}},out};
+
+ round_sd #(.WIDTH_IN(int_width),.WIDTH_OUT(WIDTH)) round_sd
+ (.clk(clk), .reset(rst), .in(integrator), .strobe_in(1'b1), .out(quantized), .strobe_out());
+
+ add2_and_clip_reg #(.WIDTH(WIDTH)) add2_and_clip_reg
+ (.clk(clk), .rst(rst), .in1(in), .in2(-quantized), .strobe_in(1'b1), .sum(out), .strobe_out());
+
+endmodule // rx_dcoffset